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OF  THE 

UNIVERSITY 

OF 


Edward  Wiley  Duckwall 
Director  of  the  National  Canners'  Laboratory,  Aspinwali,  Pa. 


Canning  and  Preserving 

of  Food  Products  with 

Bacteriological 

Technique 


A   PRACTICAL    AND    SCIENTIFIC   HAND  BOOK 
FOR  MANUFACTURERS  of  FOOD  PRODUCTS, 
BACTERIOLOGISTS,    CHEMISTS   AND 
STUDENTS    OF    FOOD    PROBLEMS. 
ALSO    FOR    PROCESSORS   AND 
MANAGERS   OF    FOOD 
PRODUCT  MANU- 
FACTORIES 


BY 


EDWARD  WILEY  DUCKWALL,  M.  S. 

r     i 

Bacteriologist  for  The  National  Canners'  Laboratory.  Member  of  the 
Society  of  American  Bacteriologists.  Member  of  the  American  Chemical 
Society.  Member  of  the  American  Association  for  the  Advancement  of 
Science.       Bacteriologist   for   the    Health    Department,    Aspinwall,    Pa. 

/   FER^TThEDlTiON 
UNIVERSITY 


Press   of 

Pittsburgh  Printing  Company 

Pittsburgh,  Pa. 


6ENERAI 


AFFECTIONATELY  DEDICATED  TO   THE  MEMORY  OF 
MY    FATHER, 

THOMAS    DUCKWALL, 

WHO  WAS  THE  PIONEER  CANNER  AND  MANUFACTURER 
OF  FOOD  PRODUCTS  IN  OHIO. 


Copyright  1905 

by 

Edward  W.  Duckwall 


V 


Contents 


Chapter  1. 
The  Laboratory  and  Its  Equipment ii 

Apparatus  Used  in  a  Bacteriological  and  Food  Laboratory,  De- 
scription of  Lenses,  Table  of  Reagents. 

Chapter  II. 
Bacteria     33 

Description  and  Classification,  Spore  Formation,  Nature  of 
Bacteria,  Influence  of  Electricity  on  Bacteria,  Influence  of 
Temperature,  Influence  of  Light,  Motility,  Chromogenic 
Bacteria,  Bacterial  Products;   Slime,  Ropiness,  etc. 

Chapter  III. 
Principles  of  Bacteriological  Technique ^2 

Methods  of  Cultivating  Bacteria,  Artificial  Media,  Method  of 
Cultivating  Anaerobes,  Methods  of  Simple  Staining,  Meth- 
od of  Staining  Flagella,  Method  of  Making  Photomicro- 
graphs. 

Chapter  IV. 
Decomposition  Caused  by  Micro-Organisms 104 

Fermentation  Theories,  Vacuum  Theory,  Alcoholic  Fermenta- 
tion, (Acetic  Fermentation),  Butyric  Fermentation,  Lactic 
Fermentation,  Putrefaction,  Reprocessing  Leaks  a  Danger- 
our  Proceeding. 

Chapter  V. 
Decomposition  Caused  by  Micro-Organisms   (Con- 
tinued)            161 

Putrefaction,  Bacteria  of.  Ptomaines  and  Toxins,  Pathogenic 
Bacteria  and  Their  Actions  on  Foods. 

Chapter  VI. 
Sterilization     208 

Nature  of  Spores,  Cleanliness  in  Manufacturing,  Disposition  of 
Waste  Material,  The  Venting  Process,  The  Vacuum  Ma- 
chinery, Discontinuous  Sterilization,  Preservatives  Formed 
in  Sterilization. 

Chapter  VII. 
Preservatives      225 

What  are  Preservatives?  Preservatives  are  not  Ordinarily 
Used  in  Canned  Goods,  Some  Food  Products  Require  Them, 
Natural  Origin  of  Preservatives  in  Food  Products,  Statements 
Made  by  Various  Authorities  Analyzed  and  Criticized, 
Sterilized  Catsup,  Preserves  and  Fruit  Butters  not  Satis- 
factory to  the  Trade,  Some  Opposing  Arguments  Answered. 


contents 

Chapter  VIII. 

Preservatives  (Continued)    247 

Experiments  with  Preservatives  and  Other  Substances  to  De- 
termine Their  Effect  on  Peptic  Digestion,  Physiological 
and  Pathological  Research  Work  with  Animals  Fed  on 
Salicylic  and  Benzoic  Acids;   Post  Mortems;   Conclusions. 

Chapter  IX. 
Chemical  Antiseptics    286 

Benzoic  Acid,  Methods  of  Detection,  Salicylic  Acid,  Methods  of 
Detection,  Formaldehyde,  Methods  of  Detection,  Boracic 
Acid,  Methods  of  Detection,  Miquel's  Table  of  Antiseptics 
and  Their  Relative  Value. 

Chapter  X. 
Artii^iciai,  Sweeteners  and  Adulterants 297 

Saccharin,  Method  of  Detection,  Dulcin,  Method  of  Detection, 
Glucin,  Sulphites,  Method  of  Detection,  Artificial  Colors, 
Starch,  etc. 

Chapter  XL 
The  Canning  Industry 311 

a  Short  History,  Location  and  Equipment  of  a  Canning  Fac- 
tory, What  to  Can,  Selection  of  Raw  Material. 

Chapter  XIL 
Peas     324 

History,  Growing,  The  Leguminous  and  Nitrifying  Bacteria, 
The  Pea  Parasite,  Chemical  Composition  and  Food  Value 
of  Peas,  Methods  of  Canning,  Machinery,  Bacteria  Asso- 
ciated with  Spoilage  Found  in  Various  Actual  Losses. 

Chapter  XIII. 
Tomatoes      398 

Character  of  Tomatoes  Raised  in  Different  Localities,  Method 
of  Canning,  Cold  Packed  Tomatoes,  Sour  Tomatoes  Due  to 
Souring  Before  the  Sterilizing  Process;  the  Cause  and  Rem- 
edy, An  Attempt  to  Pack  Tomatoes  in  a  Vacuum  Jar,  with- 
out Sterilization;  Cause  of  the  Spoilage,  Bacteria  the  Cause 
of  Tomato  Black-rot  Disease,  Uneven  Temperature  in  the 
Process,  Resulting  in  Loss. 

Chapter  XIV. 
Corn 418 

a  Short  Historical  Sketch,  The  Canning  of  Corn,  Suggestions 
for  Canning  and  Processing,  Cause  of  Sour  Corn,  Labora- 
tory Work  on  Spoilage  Cases,  Spoilage  Due  to  Poor  Tin 
Plate,  Spoilage  Due  to  Imperfect  Circulation  in  the  Process, 
Bacteria  Which  Cause  Souring  of  Corn,  Insufficient  Sterili- 
zation and  Its  Results,  Discoloration  of  Corn  Due  to  Prod- 
ucts Elaborated  by  Bacteria;  Other  Causes,  Method  of  Sep- 
arating Sour  Corn  from  Good,  Method  of  Determining 
Cause  of  Spoilage,  whether  Leaks  or  Insufficient  Sterili- 
zation. 


PREFACE 


THERE  are  many  valuable  works  written  on  the  general 
subject  of  bacteriology,  but  nearly  all  such  text-books 
apply  the  science  either  directly  or  indirectly  to  the  field 
of  medicine  and  surgery.  Few  authors  have  given  any 
considerable  space  to  the  study  of  non-pathogenic  bacteria,  and 
very  little  attempt  has  been  made  to  describe  these  species,  beyond 
a  few  typical  forms  mentioned  by  the  old  authors. 

While  the  pathogenic  bacteria  are  occasionally  found  associated 
with  the  spoilage  of  food  products,  the  non-pathogenic  bacteria  are 
far  more  common.  Some  of  the  pathogenic  bacteria  produce  pto- 
maines and  toxins  in  various  food  products,  having  gained  entrance 
through  contamination  with  diseased  persons  and  animals,  but  these 
cases  are  extremely  rare,  owing  to  the  rigid  inspection  of  such 
products  as  are  most  liable  to  infection.  Putrefactive  bacteria  are 
more  commonly  active  agents  in  the  production  of  ptomaines. 

In  this  work  we  have  endeavored  to  outline  a  course  of  study 
in  bacteriology  which  will  be  particularly  useful  to  the  manufac- 
turer and  the  student  of  food  products.  The  causes  of  spoilage  are 
defined,  and  the  first  volume  is  designed  particularly  to  enable  the 
student  to  gain  a  general  knowledge  of  bacteriology  which  may  be 
applied  directly  to  solving  problems  of  spoilage. 

In  the  general  plan  have  been  introduced  various  well-known 
species  of  bacteria  for  comparative  study,  because  the  descriptions 
are  given  fully  in  nearly  all  text-books  and  the  beginner  will  be 
better  fitted  for  isolating  and  studying  new  species  after  he  has  com- 
pleted a  study  of  the  well-known  species. 

There  has  been  no  attempt  to  classify  or  name  many  of  the 
new  species  which  were  found  associated  with  food  spoilage,  but 
the  author  has  been  satisfied  to  describe  the  action  of  these  species 
on  various  food  substances  and  has  endeavored  to  ascertain  the  heat- 
resisting  power  of  various  spores. 

The  first  volume  of  this  work  is  designed  especially  to  assist 
the  student  in  a  laboratory  course  in  bacteriology  applied  to  the 
manufacture  of  food  products,  particularly  Canning  and  Preserv- 
ing. The  half-tones  introduced  as  illustrations  were  made  from 
photomicrographs  taken  by  the  author  from  specimens,  stained  and 
mounted,  which  were  either  isolated  directly  from  spoiled  food 
products  or  obtained  through  the  courtesy  of  co-workers. 

Several  cultures  of  pathogenic  bacteria  were  kindly  furnished 
by  Dr.  F.  G.  Novy  of  the  University  of  Michigan,  and  these  were 


8  PREFACE 

stained,  mounted  and  photomicrographed  for  illustrations  in  this 
book. 

Chemical  methods  of  analysis  have  been  introduced  for  the 
benefit  of  the  student.  Some  of  these  tests  are  very  useful  in  the 
study  of  the  products  of  fermentation  and  putrefaction.  Other 
tests  are  given  for  the  detection  of  adulterations  and  preservatives, 
all  necessary  for  the  study  of  food  products. 

In  the  beginning  is  a  description  of  the  microscope,  lenses,  ap- 
paratus, etc.,  employed  in  different  parts  of  the  work,  together  with 
a  complete  table  of  reagents  used  in  the  various  preparations  and 
chemical  tests. 

Then  follows  the  description  and  classification  of  bacteria  and 
methods  of  cultivating  and  staining.  The  method  given  for  stain- 
ing flagella  is  that  employed  by  the  author,  with  success.  The 
various  forms  of  decomposition  are  carefully  studied,  the  last  of 
which  is  the  study  of  Putrefactive  and  Pathogenic  organisms  and 
the  poisonous  products  elaborated  by  them. 

Sterilization  has  been  carefully  studied  in  all  its  bearings,  in- 
cluding Cleanly  Methods  of  Manufacture  and  the  Disposition  of 
Waste  Material. 

Considerable  space  is  devoted  to  the  subject  of  Preservatives; 
their  natural  origin ;  their  formation  in  canned  goods  during  sterili- 
zation. This  subject  has  been  studied  by  the  author  and  his  assis- 
tants by  feeding  various  animals  stated  daily  amounts  in  their  food 
for  different  periods  of  time.  The  feeding  terms,  weights  and  path- 
ological effects  on  the  internal  organs,  are  faithfully  described.  Var- 
ious theories  of  physicians  and  authorities  of  the  harmful  effect  of 
these  substances  and  their  effect  on  processes  of  digestion  have  been 
analyzed.  Many  of  these  theories  have  been  completely  upset  by 
actual  tests  and  by  force  of  argument.  Throughout  the  whole 
subject,  the  author  has  been  faithful  to  facts  as  he  found  them,  and 
mere  theories  without  the  support  of  actual  experiments  and  proofs 
have  been  criticised. 

Whatever  may  be  true  as  to  the  effect  of  at  least  two  preser- 
vatives upon  the  human  organism,  no  proofs  of  their  harmfulness 
have  been  produced, — the  preservatives  studied  in  this  connection  are 
Salicylic  and  Benzoic  Acids. 

So  far  as  I  know,  no  person  has  come  forward  with  the  state- 
ment that  he  has  ever  been  harmed  in  the  least  by  eating  them  in 
table  luxuries.  The  fact  that  thousands  of  tons  of  these  two  pre- 
servatives have  been  used  by  people  who  were  under  actual  observa- 
tion of  the  manufacturers,  and  the  fact  that  no  experiments  with 
animals  have  produced  pathological  changes,  seems  to  indicate  that 
much  of  the  hue  and  cry  against  them  is  not  well  founded. 


PREFACE  9 

Methods  are  given  for  extracting  varous  preservatives;  also 
artificial  sweeteners;  also  Miguel's  table  of  Antiseptics  and  their 
value. 

Artificial  colors  are  not  approved,  and  methods  for  detecting 
them  are  given. 

The  last  part  of  this  volume  is  taken  up  with  the  study  of  the 
canning  of  peas,  tomatoes  and  corn.  For  twenty  years  the  author 
has  had  practical  experience  in  canning  and  preserving,  having  had 
charge  of  these  departments  for  two  of  the  largest  houses  in  Ameri- 
ca, so  that  the  practical  and  the  scientific  knowledge  of  his  subject 
are  brought  closely  together. 

Considerable  space  has  been  devoted  to  the  results  obtained  by 
bacteriological  and  chemical  analyses  of  various  spoilage  cases  to- 
gether with  suggestions  made  to  correct  imperfect  methods. 

Some  laboratory  work  on  tin  plate  is  reproduced.  The  author 
has  endeavored  to  show  the  action  of  fruits  and  vegetables  on  tin 
plate.  Quantitative  analyses  of  new  tin  plate  were  made,  and  the 
half-tones  illustrate  the  imperfections  as  they  appear  on  the  ordinary 
plate  used  for  canning  purposes. 

While  this  volume  does  not  take  in  the  whole  list  of  canned 
and  manufactured  food  products,  in  another  valume  the  data  at 
hand  and  the  results  obtained  from  the  investigation  conducted  dur- 
ing the  coming  year  will  be  published. 

Edward  W.  Duckwat.l. 

Aspinwall,  Pa.,  Sept.  i,  igo5. 


MICROSCOPE 


Canning  and  Preserving  of  Food 
Products  with  Bacteriolo- 
gical Technique 


CHAPTER  I. 


The  Laboratory  and  its  Equipment 

The  Laboratory  and  Its  Equipment.  Apparatus  Used  in  a 
Bacteriological  and  Food  Laboratory.  Description  of  Lenses. 
Table  of  Reagents. 

THE  microscope:. 

THE  MICROSCOPE  is  the  most  useful  instrument  needed  for 
this  work,  and  its  selection  is  important  in  order  to  get  the  best  pos- 
sible combination  of  good  qualities.  No.  lo  stand,  objectives,  and 
other  attachments  made  by  the  Spencer  Lens  Company,  of  Buffalo, 
N.  Y.,  give  excellent  satisfaction.  The  microscope  requires  care- 
ful attention ;  it  should  always  be  kept  in  a  tidy  condition,  and  it  is 
quite  necessary  to  know  how  to  take  care  of  the  instrument  in  order 
that  its  delicate  parts  may  not  be  injured.  The  stand  shown  in  the 
cut  has  a  handle,  by  means  of  which  it  may  be  carried,  but  most  mi- 
croscopes do  not  have  this  convenience  and  they  must  be  lifted  by  the 
pillar  below  the  level  of  the  stage,  and  never  by  the  fine  adjustment 
tube  or  by  the  barrel.  The  lacquer  of  a  microscope  is  injured  by 
finger  marks  and  should  not  be  touched.  Finger  marks  may  be  re- 
moved by  breathing  on  the  parts  and  gently  rubbing  with  chamois 
skin.  No  chemical,  such  as  alcohol  or  xylol,  should  be  used  to  re- 
move the  marks,  because  it  may  remove  the  lacquer  also.  The  mi- 
croscope is  provided  with  milled  parts,  which  are  the  only  parts  to  be 
handled  when  working. 

The  stage  of  the  microscope  should  be  kept  clean  and  free  from 
water.  During  the  examination  of  live  cultures  of  bacteria  it  may 
happen  that  some  of  the  culture  will  get  on  the  stage.  It  should  be 
carefully  removed  with  a  rag  moistened  with  bichloride  of  mercury 
solution. 

OBJECTIVKS. 

The  objectives  are  of  two  kinds,  the  dry  and  the  oil  immersion. 
The  dry  objectives  should  be  kept  clean  with  dry  lens  paper;  they 
should  never  be  allowed  to  touch  oil,  water  or  other  substances. 
The  oil  immersion  lens  is  very  delicate  and  easily  injured.  It  should 


12 


CANNING    AND    PRESERVING    OP    FOOD    PRODUCTS. 


never  be  used  dry,  but  always  with  a  drop  of  cedar  oil,  and  in  the 
manipulation  it  should  never  be  forced  down  against  the  glass  slide 
or  cover  glass.  Each  evening  after  work  the  cedar  oil  should  be  re- 
moved from  this  objective  by  means  of  lens  paper,  moistened  with 
xylol  and  dried  with  soft  linen  or  lens  paper.  Alcohol  or  other 
chemicals  should  never  be  used  for  fear  of  dissolving  the  cement 
which  holds  the  lens. 

STANDS. 

The  selection  of  a  stand  is  important,  and  while  it  may  not  be 
expensive  it  should  be  strong  and  firm  in  all  its  bearings.  If  pho- 
tomicrographs are  to  be  taken,  the  stability  of  the  stand  must  be 


Cone,  fine  adjustment 


first-class.  The  Une  adjustment  is  important.  One  cannot  realize 
this  until  he  begins  to  take  photomicrographs.  Many  of  the  fine 
adjustment  schemes  are  very  unreliable  and  are  easily  jarred  out  of 
focus,  particularly  when  the  microscope  is  in  a  horizontal  position. 
There  is  a  new  fine  adjustment  which  is  operated  by  a  cone.  This 
is  so  sensitive  that  the  definitions  of  the  reading  drum,  mark  a  ver- 
tical movement  of  the  tube  of  0.002  millimeters.  This  is  a  g-reat 
advantage  and  is  appreciated  by  the  operator  when  making  photomi- 
crographs. 


THE   LABORATORY   AND   ITS   EQUIPMENT. 
MECHANICAI,   STAGE. 


13 


A  MECHANICAL  STAGE  is  very  useful  and  almost  indis- 
pensable.    The  one  shown  in  the  cut  gives  an  extended  lateral  move- 


Fig.  2.     Mechanical  Stage 


ment  and  the  verniers  are  graded  to  read  o.i  m.  m.,  and  are  placed 
closely  together  so  as  to  be  read  at  a  glance.  The  mechanical  stage 
has  the  advantage  of  holding  in  a  steady  position  a  particularly  in- 
teresting view.  It  is  also  valuable  in  searching  the  field,  which  can 
be  done  systematically  and  with  great  precision. 

OBJECTIVES. 

OBJECTIVES  are  of  two  kinds,  the  dry  and  the  oil.  The 
dry  objectives  are  seldom  made  in  powers  higher  than  y%  inch.  For 
fine  work,  the  apochromatic  objectives  are  preferable  to  any  others 
on  account  of  their  greatly  superior  correction  of  spherical  and 
chromatic  aberrations,  which  gives  fine  definition.  The  resolving 
power  is  also  greater  than  the  achromatic  on  account  of  their  higher 
numerical  aperture,  but  for  ordinary  work  the  achromatic  objectives 
answer  very  well. 


14 


THE  LABORATORY   AND   ITS  EQUIPMENT. 
MICROMETER  EYEPIECE. 


For  measuring  objects  under  the  objective  it  is  advisable  to 
use  both  the  micrometer  eyepiece  and  stage  micrometer. 


Fig.  3.     Spencer  Micrometer  Eyepiece 


DESCRIPTION  OE  LENSES. 


Lenses  are  of  two  kinds,  simple  and  compound;  the  former 
is  generally  a  single  lens.  A  simple  microscope  is  therefore  a 
simple  lens.  The  rays  of  light  come  directly  from  the  object  to 
the  eye  and  a  Virtual  Image  is  produced.  (See  figure  4,  by  Carpen- 
ter.)    This  illustrates  the  simple  microscope. 


Fig.  4.       Virtual  Image,   Simple  Microscope   (Carpenter) 

The  object  is  placed  between  the  focus  and  the  lens.  This 
figure  also  illustrates  the  action  of  the  eyepiece  in  the  compound 
microscope.  If  the  object  is  placed  beyond  the  principal  focus  (p) 
a  real  image  results,  as  is  shown  in  figure  5.  This  illustrates  the 
action  of  the  objective  in  the  compound  microscope.  In  the  com- 
pound miscroscope  there  are  two  sets  of  lenses,  the  eyepiece  and 
the  objective;  the  latter  is  nearest  the  object  and  produces  a  real 


CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 


Real  Image  (Carpenter) 


15 


image,  as  shown  in  figure.  The  image,  however,  is  inverted  and 
reversed ;  the  light  is  inside  the  principal  focus  of  the  eyepiece  and 
rays  of  light  leave  it  if  they  come  from  a  real  object.    The  image 


Fig.  6.     Principle  of  a  Compound  Microscope  (Carpenter) 

F — Object  in  focus.       O — Objective  with  diaphragm.       AB— Real  image  of  F,  in  the  opening  of  the  diaphragm; 
above  this  is  a  compensating  ocular  which  magnifies  the  real  image  AB,  this  forming  the  virtual  image  CD 


16  CANNING    AND    PRESERVING    OP    FOOD    PRODUCTS. 

lying  inside  of  the  principal  focus  becomes  magnified  by  the  eye- 
piece (e)  and  the  Virtual  Image  (c  d)  is  produced. 

Roger  Bacon,  an  English  monk,  is  said  to  have  been  the  first 
man  to  recognize  the  peculiar  properties  of  a  lens,  in  1276.  The 
simple  lens  was  used  in  the  construction  of  spectacles.  In  the 
seventeenth  century  the  microscope  was  perfected  sufficiently  to 
discern  bacteria.  Galileo  made  a  compound  microscope  in  the  year 
1 610,  and  a  cut  of  this  microscope  is  shown,  by  Carpenter.  This 
microscope  contained  a  single  lens  for  an  objective  and  a  single 
lens  for  an  eyepiece.  The  rays  from  the  single  lens  do  not  meet 
in  the  same  plane  and  spherical  aberration  results.  The  rays  of 
light  are  also  decomposed  in  a  simple  lens,  which  acts  as  a  prism; 
the  violet  is  bent  most  and  is  brought  to  a  focus  at  a  different 
point  from  the  red  ray,  which  is  bent  the  least.  A  fringe  of  colors 
results,  and  this  is  designated  as  ''chromatic  aberration".  The 
spherical  chromatic  aberrations  are  corrected  in  the  best  instru- 
ments now  made  by  means  of  diaphragms  and  stops  and  combina- 
tions of  different  kinds  of  glass.  The  chromatic  aberration  is  fair- 
ly well  corrected  by  the  combination  of  the  two  glasses,  Crown 
and  Flint,  and  the  objectives  made  from  this  combination  are  called 
Achromatic.  Still,  in  the  achromatic  objective  there  is  not  absolute 
freedom  from  color.  Even  if  some  of  the  rays  are  neutralized, 
another  will  remain,  and  a  certain  amount  of  color  will  show  in 
the  image  in  the  achromatic  objective.  This  is  designated  as  *'sec- 
ondary  spectrum."  In  order  to  overcome  this  color,  Abbe  and 
Zeiss  in  1889,  prepared  special  kinds  of  glass,  the  so-called  "borate" 
and  "phosphate"  glass,  and  this  combination  in  objectives  was 
designated  as  "apochromatic."  Fluorite  is  also  used  in  some  apo- 
chromatics  and  the  secondary  spectrum  is  thus  corrected.  This 
correction  is  disturbed  somewhat  by  the  cover-glass^  which  re- 
fracts the  peripheral  rays  as  they  enter  the  objective  and  they  seem 
to  come  from  a  point  nearer  the  objective  than  do  the  central  rays. 
In  order  to  overcome  this  the  objectives  are  made  "under-correct- 
ed," so  that  both  points  are  focused  at  once.  In  order  to  get  uni- 
form results  it  is  well  to  use  cover-glasses  of  uniform  thickness  for 
the  oil  immersion  objectives. 

The  most  important  part  of  the  microscope,  therefore,  is  the 
objective,  and  great  care  should  be  exercised  in  making  a  selection 
in  order  to  get  the  best  results.  While  good  magnifying  power 
is  always  desirable,  it  is  of  less  value  than  the  defining,  resolving 
and  penetrating  power.  A  proper  magnifying  power  is  necessary, 
and  it  is  customary  to  speak  of  an  objective  as  a  ^,  J^,  J^,  J^, 
I -1 2,  etc.  Some  makers  use  these  figures,  others  use  letters,  and 
some  designate  the  magnifying  power  by  millimeters.  Every  ob- 
jective has  what  is  called  an  initial  magnification,  and  this  initial 
magnification  is  multiplied  by  the  magnifying  power  of  the  eye- 


THE   LABORATORY    AND   ITS   EQUIPMENT.  17 

piece  used.  For  instance,  if  the  initial  magnifying  of  a  1-12  ob- 
jective is  125,  when  a  No.  8  eyepiece  is  used,  the  magnification 
will  be  1,000  diameters.  Magnification  is  always  meant  as  linear 
in  scientific  work,  magnification  being  expressed  as  so  many  di- 
ameters. For  instance,  if  a  magnification  is  expressed  as  1,000 
diameters,  the  superficial  area  magnification  would  be  1,000,000. 


THE  DEFINING  POWER. 

It  is  difficult  to  secure  perfect  flatness  of  field.  This  is  over- 
come to  some  extent  by  compensating  eyepieces.  Flatness  of  field 
is  very  essential  in  making  photomicrographs.  Probably  the  most 
important  qualities  of  the  microscope  are  its  resolving  and  pene- 
trating power.  These  are  the  qualities  which  show  up  the  fine 
markings  and  delicate  structures.  These  qualities  have  no  refer- 
ence to  the  magnifying  power.  The  light  which  enters  the  ob- 
jective has  much  to  do  with  its  resolving  power. 


Fig.  7 
Arrangement  of  Lenses  in  a  2  millimeter  or  jV  Oil  Immersion  Objective  (Carpenter) 

A — Angle  of  Aperture 

The  light  which  enters  the  objective  is  included  between  the 
extreme  rays,  and  an  angle  is  formed  by  the  extreme  rays  with 
the  object  in  focus,  and  this  angle  is  known  as  the  '*angle  of  aper- 
ture," shown  by  (a)  in  Fig.  7.  Fig.  7  shows  the  system  of  lenses 
as  they  are  arranged  in  the  oil  immersion  objective.  On  account 
of  the  number  of  lenses  employed,  tlie  light  becomes  very  faint,  and 
it  is  therefore  necessary  to  admit  as  much  light  as  possible.  The 
improvement  of  an  oil  immersion  lens  over  a  dry  objective  is  due 
to  the  fact  that  the  light  passing  from  the  object  in  focus  into  the 
cover-glass  is  somewhat  refracted,  and  unless  it  is  collected  again 
much  of  it  is  lost.  Amici  introduced  the  water  immersion  objec- 
tive. This  was  an  improvement  over  the  dry  objective  from  the 
fact  that  water  would  collect  the  rays  of  light  fairly  well,  but  in 
1878  Stephenson  suggested  cedar  oil,  which  has  the  same  index  of 
refraction  as  crown  glass,  and  this  has  been  in  use  ever  since.     A 


18 


CANNING    AND    PRESERVING    OP    FOOD    PRODUCTS. 


high  numerical  aperture  is  then  most  vahiable  and  objectives  thus 
constructed  are  the  most  expensive. 

The  penetrating  power  of  an  objective  depends  upon  its  abiHty 
to  show  up  objects  in  different  planes.  It  is  more  highly  perfected 
in  the  lower  powers  and  there  is  still  room  for  great  improvement. 
In  the  examination  of  molds  every  worker  is  somewhat  handicap- 
ped on  account  of  improper  penetrability. 

ABBE  CONDENSER. 

A  most  important  accessory  to  the  microscope  is  the  Abbe 
condenser.  There  are  two  special  makes,  the  chromatic  and  the 
achromatic.  The  first  is  suitable  for  ordinary  work,  but  for  photo- 
micrography the  achromatic  is  almost  indispensable.  Fig.  8  shows 
a  condenser  of  special  construction,  which  can  be  swung  out.  Two 
diaphragms  ordinarily  go  with  it,  one  above  and  one  below,  and 


Fig.  8.     Abbe  Condenser 

in  addition  to  these  there  is  a  special  arrangement  made  for  hold- 
ing the  polariscope  and  other  accessories  for  special  illumination. 
The  mirror  under  the  Abbe  condenser  is  plain  on  one  side  and 
concave  on  the  other,  the  concave  side  being  used  to  illuminate 
specimens  in  a  living  state,  and  the  light  is  regulated  with  the 
iris  diaphragm.  The  direct  rays  of  the  sun  should  never  be  used. 
Some  writers  prefer  the  light  from  a  white  cloud,  but  more  uni- 


THE   LABORATORY   AND   ITS   EQUIPMENT. 


19 


form  results  are  obtained  from  the  Welsbach  light.  After  one  be- 
comes accustomed  to  this  light  it  becomes  easier  to  make  compara- 
tive study.  For  photomicrography  the  electric  light  is  frequently 
employed,  but  the  acetylene  light  is  better  in  every  respect,  because 
the  details  are  more  clearly  brought  out. 


PHOTOMICROGRAPHIC    CAMERA. 


This  need  not  be  an  expensive  apparatus.     The  one  shown  in 
Plate  2  is  well  suited  for  the  work,  because  the  camera  and  opti- 


Plate  2,     Photomicrographic  Camera 


cal  bench  are  solidly  and  conveniently  held  by  a  single  support,  giv- 
ing them  stability  and  perfect  alignment  without  the  risk  of  its 
disturbance. 

In  making  good  photomicrographs  there  are  several  points 
which  must  be  carefully  borne  in  mind  in  order  to  secure  good 
results:  First,  a  good  slide  preparation;  second,  a  good  miscro- 
scope  stand,   provided  with  objectives  and   eyepieces,   having  the 


20 


CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 


qualities  described  under  the  head  of  "The  Microscope;"  a  proper 
screen,  acetylene  Hght,  and  first-class  isochromatic  or  orthochro- 
matic  plates.  The  development  of  the  plates  and  the  printing  are 
all  well  understood  by  anyone  familiar  with  photography. 


THE  INCUBATOR. 

The  one  shown  in  the  cut  is  admirably  adapted  for  the  cultiva- 


Fig.  9.     Incubator 

tion  of  bacteria.  To  this  must  be  attached  a  thermostat,  which 
can  be  regulated,  so  that  any  desired  temperature  may  be  main- 
tained constantly.  This  apparatus  is  very  necessary  in  the  cultiva- 
tion of  a  great  variety  of  bacteria  and  the  usual  temperature  em- 
ployed is  98°F.,  although  for  special  organisms  a  room  tempera- 
ture is  better.    The  incubator  should  be  provided  with  a  glass  door 


THE   LABORATORY    AND   ITS   EQUIPMENT. 


21 


SO  that  cultures  may  be  observed  without  opening  excepting  when 
it  is  absolutely  necessary.  Heat  is  supplied  by  the  Koch's  safety 
burner,  which  turns  off  the  gas  supply  automatically  in  case  of  ac- 
cident. For  testing  canned  goods  to  determine  if  the  sterilizing 
process  has  been  sufficient  the  incubator  is  almost  indispensable. 


THE  AUT0CI.AV. 


This  apparatus  resembles  in  many  respects  the  ordinary  steam 
retort  vised  in  every  cannery.  A  little  water  covers  the  bottom 
and  steam  is  generated  by  means  of  a  triple  Bunsen  burner,  so  that 
any  desired  temperature  can  be  raised.     As  shown  by  the  cut  the 


Fig.  10 

top  is  arranged  so  that  it  can  be  clamped  down,  and  a  safety  valve, 
thermometer  and  steam  gauge  are  attached  to  the  top  so  that  they 
may  be  easily  seen.  This  apparatus  is  used  for  sterilization  of  all 
culture  media,  and  such  media  as  are  not  injured  by  high  tem- 
peratures are  sterilized  in  one  operation,  where  four  or  five  opera- 
tions are  required  in  the  laboratory  not  equipped  with  the  auto- 
clav.  It  affords  an  excellent  means  of  determining  the  heat  re- 
sisting power  of  various  spores. 


22  CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 

THE  centrii^uge:. 


Fig.  11 

This  apparatus  is  used  in  the  laboratory  for  various  purposes. 
It  is  ahiiost  indispensable  for  breaking  up  emulsions  formed  by 
solvents  in  determining  the  presence  of  preservatives  in  food  prod- 
ucts. It  is  also  useful  in  separating  blood  serum  from  the  corpus- 
cles. It  is  useful  in  precipitating  the  tubercule  bacilli  from  sputum 
made  into  emulsions.  It  is  used  frequently  in  determining  the 
presence  of  fat  in  milk,  cream,  cheese  and  other  substances. 


DISTILLING  APPARATUS. 


Fig.   12.     Distilling  Apparatus 

This  apparatus  is  necessary  for  distilling  water  and  other  sub- 
stances where  a  clear  solution  is  desired.  It  is  made  of  heavy 
copper,  is  lined  w'ith  movable  head,  and  the  condensing  worm  is 
made  of  pure  block  tin. 


THE   LABORATORY   AND   ITS   EQUIPMENT.  23 

ANALYTICAL  SCALES. 


Balances 


These  balances  are  graduated  in  loo  divisions  for  i  m.m.  and 
show  the  sensibility  of  1/200  m.  g.  The  beam  and  its  hangings 
are  of  pure  aluminum ;  the  bearings  are  of  agate  with  agate  knives. 
These  balances  are  used  in  fine  analytical  work,  such  as  the  deter- 
mination of  the  amount  of  tin  used  on  tin  plate  and  the  weighing 
of  minute  quantities  of  any  chemical.  Such  a  balance  is  indispen- 
sable in  a  well-equipped  laboratory. 

WATER  BATH. 


Fig.  14.     Water  Bath 

This  apparatus  is  employed  for  evaporating  substances  which 


24 


CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 


are  affected  by  more  intense  heat.     There  is  probably  no  apparatus 
in  the  laboratory  which  is  employed  more  constantly  than  this. 


FARAB^FINE    BATH. 


Fig.  15.     Paraffine  Bath 

This  bath  is  very  useful  for  high  temperatures  and  is  the  one 
employed  for  the  conversion  of  saccharin  into  salicylic  acid.  It  is 
very  useful  where  temperatures  running  from  i2o°to  25o°C,  are 
required. 


FORCEPS. 


Fig.   16.     Cornet  Forceps 


^^^^33 


Fig.   17.     Novy  Forceps 


THE   LABORATORY    AND   ITS   EQUIPMENT. 


25 


The  two  cuts  show  the  character  of  the  forceps  used  generally 
in  bacteriological  work.  The  Novy  forceps  are  convenient  for 
handling  cover-glasses,  w^hile  the  Cornet  are  large  and  firm  and 
are  so  constructed  that  they  will  hold  stains  in  fluid  form  on  the 
cover-glass,  so  that  they  will  not  run  down  underneath  nor  onto 
the  forceps. 


THE  MICROTOME. 


BUFFALO.   N.  Y 


Plate  3.     Microtome 


26 


CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 


This  apparatus  is  used  for  making  sections  of  the  internal 
organs  of  such  animals  as  Guinea  pigs,  rabbits,  etc.,  shown  in 
chapter  on  preservatives.  The  feed  is  controlled  by  an  adjustable 
cam  having  a  scale  marked  with  a  number  of  teeth,  providing  for 
any  thickness  of  section  from  one  up  to  twenty-five  microns  or 
more,  and  is  absolutely  reliable.  The  sections  which  are  photo- 
graphed in  this  volume  were  cut  from  one  to  two  microns  in  thick- 
ness. For  bacteriological'  and  pathological  work  this  apparatus  is 
indispensable. 


List  of  Apparatus  and  Chemicals 


1  Agar  apparatus. 

1  Acetylene   gas  generator  and  burn- 
ers. 

Anaerobic  culture  apparatus. 
Animal  Holder. 
Asbestos  pads. 
Aspirator. 
Autoclav. 
Nest  of  Beakers. 

Blast   lamp,    bottles,    various    sizes, 
colored  glass. 

6  Boxes  slides  for  microscope. 
12  Boxes  for  test  tube  cultures. 

2  Burettes,  50  c.  c. 
Burettes,  100  c.  c. 
Burette  stands. 
Buto-refractor. 
Burners,  Bunsen. 
Centrifuge,  Babcock's. 
Chamberlain  filter. 

Cheesecloth. 

1  Colony  counter. 

Copper  soldering  iron. 

Corks,  assorted  sizes. 

Cotton  roll,  absorbent. 

ozs.  Cover-glasses,  No.  1. 

Crucible. 

Cylinder,  25  c.  c.  graduated. 

Cylinder,  50  c.  c.  graduated. 

Cylinder,  100  c.  c.  graduated. 

Cylinder,  500  c.  c.  graduated. 

Cylinder,  1000  c.  c.  graduated. 

Dessicator. 

Disinfecting  jar. 


1  Distilling  apparatus. 

4  Enameled  pans,  nested. 

12  Esmarch  dishes. 

100  Filter  paper,  circles,  20  cm. 

100  Filter  paper,  circles,  32  cm. 

100  Filter  paper,  circles,  15  cm. 

1  Square  yard  Flannel. 

G  Flasks.  Erlemeyer  vacuum. 
12  Flasks,  Florentine,  500  c.  c. 

2  Funnels,  large. 
2  Funnels,  15  cm. 
2  Forceps,  Novy. 

G  Forceps,  Cornet. 

2  Glass  stiring  rods. 

G  Glass  slides,  hollow  ground. 

500  g.  Glass  tubing,  4mm.  diam. 

500  g.  Glass  tubing,  6mm.  diam, 

500  g.  Glass  tubing,  8mm.  diam. 

500  g.  Glass  tubing,  22mm.  diam. 

1  Hot  pan. 

1  Hydrogen  generator,  Kipp's. 

1  Hydrogen  sulphide  generator. 

1  Incubator,  large,  complete. 

Labels,  slide,  jar  and  bottle. 

1  Magnifier,  simple  lens. 

1  Micrometer,  cross-wire  ocular. 

1  Micrometer  eyepiece. 

1  Micrometer,  stage. 

1  Microscope,  Spencer,  No.  10  stand. 

1  Mechanical  stage,  Spencer. 

4  Eyepieces,  4,  G,  9,  12,  compensating. 

4  Objectives,     2-3,      1-6,      1-12,      1-16, 

apochromatic. 
1  Abbe  condenser,  achromatic 


THE   LABORATORY   AND   ITS   EQUIPMENT. 


27 


1  Triple  nose  piece. 

1  Bull's  eye,  3  in. 

1  Microtome,  Spencer. 

1  Paraffine  bath. 

1  gross  Petri-dishes,  various  sizes. 

1  Photomicrograph  camera,   Spencer. 

6  Pipettes,  various  sizes. 

3  Platinum  wires  in  glass  rods. 

1  Polariscope. 

6  Porcelain  dishes,  nested. 
3  Knives,  peeling. 

2  Retort  stands. 

Rubber  stoppers,  various  sizes. 
1  Sand  bath. 

1  Scissors,  14cm. 

2  Separatory  funnels. 
1  Shears,  tin. 

1  Syringe,  5  c.  c.  inoculating. 
200  Test  tubes,  12  X  125  mm. 
200  Test  tubes,  15  X  150mm. 
24  Test  tubes,  20  X  150mm. 

2  Test  tube  brushes  for  cleaning. 
2  Thermometers,  clinical. 

1  Thermometer  for  retort. 

1  Thermometer  for  paraffine  bath. 

2  Thermo-regulators. 
2  Tripods. 

1  Wash  bottle. 

6  Watch  glasses,  5  cm. 

1  Water  bath. 

2  Wax  pencils,  blue  and  yellow. 

3  Wire  baskets,  medium. 
6  Wire  baskets,  small. 

6  Wire  cages  for  animals. 
8  Wire  gauze. 

CHEMICALS   AND   SUPPLIES 

10  grams.  Acetic  acid,  glacial. 

100  grams  Agar  agar. 

1000  grams  Alcohol,  absolute. 

1000  grams  Ammonium  hydrate. 

10  grams  Benzoic  acid. 

100     grams  Benzoate  of  sodium. 

10  grams  Boraclc  acid. 

10  grams  Borax. 

100  grams  Carbolic  acid. 


50  grams  Celloidin. 

3000  grams  Chloroform. 

100  grams  Collodium. 

10  grams  Eosin. 

3000  grams  Ether. 

50  grams  Ferric  tartrate. 

50  grams  Ferrous  sulphate. 

25  grams  Fuchsine  (not  the  acid). 

250  grams  Gelatin. 

10  grams  Gentian  violet. 

200  grams  Glucose. 

100  grams  Glycerin. 

50  grams  Hematoxylin,  Delifield's. 

2500  grams  Hydrochloric  acid. 

50  grams   lodin,   resublimed. 

30  grams  Lactose. 

50  grams  Litmus. 

Litmus  paper,  red  and  yellow. 

100  grams  Mercuric  bichlorid. 

15  grams  Methylene  blue. 

1000  grams  Nitric  acid. 

50  grams  Cedar  oil. 

50  grams  Clove  oil. 

3000  grams  Paraffin. 

200  gramas  Pepton,  Witte's. 

200  grams  Potassium  bichromate. 

200  grams  Potassium  iodide. 

5  grams  Potassium  ferrocyanide. 

100  gramas  Pyrogallic  acid. 

100  gramas   Salicylic  acid. 

500  grams  Salt. 

200  grams  Sealing  wax. 

200  grams  Sodium  carbonate. 

500  grams  Sodium  hydrate. 

500  grams  Solder. 

500  grams  Steel  filings. 

2500  grams  Sulphuric  acid. 

50  grams  Tannic  acid. 

500  grams  Tin  foil. 

50  grams  Turpentine. 

100  grams  Vaseline. 

500  grams  Xylol. 

3000  Zinc,  granulated. 

500  grams  Zinc  chlorid. 

20  grams  Canada  balsam  in  tube. 

100  pounds  Carbide  in  drum. 


28 


CANNING    AND    PRESERVING    OP    FOOD    PRODUCTS. 


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THE    LABORATORY    AND   ITS    EQUIPMENT. 


29 


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30 


OANNING    AND    PRESERVING    OP    FOOD    PRODUCTS. 


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THE   LABORATORY    AND   ITS   EQUIPMENT. 


31 


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32 


CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 


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BACTERIA.— DESCRIPTION  AND  CLASSIFICATION.  33 


CHAPTER  11. 

Bacteria— Description   and  Classification 

Spore  Formation.  Nature  of  Bacteria.  Influence  of  Electricity 
on  Bacteria.  Influence  of  Various  Temperatures.  Influence 
of  Light.  Motility.  Chromogenic  Bacteria.  Bacterial  Prod- 
ucts.    Slime,  Ropiness,  Etc. 


Bacteria  belong  to  the  lower  vegetable  kingdom  and  are  not 
properly  named  germs  or  microbes,  which  terms  embrace  a  larger 
meaning  including  animalcules  and  lower  insect  life.  In  1683 
Leeuwenhoek  made  the  discovery  of  bacteria  while  examining  the 
scraping  of  the  teeth,  and  for  nearly  two  hundred  years  bacteria 
were  thought  to  be  animal  life.  In  1875,  several  investigators, 
Cohn,  Xaegeli  and  others,  settled  the  fact  that  they  belonged  to 
the  vegetable  kingdom,  principally  on  account  of  their  resemblance 
to  the  algae  in  their  manner  of  reproduction,  growth  and  multipli- 
cation. The  distinction  between  these  low  vegetable  forms  and  the 
lowest  forms  of  animal  life  is  not  so  easily  determined  as  we  might 
suppose,  for  the  reason  that  there  are  so  many  unknown  facts 
concerning  both,  which  science  up  to  this  time  has  not  been  able 
to  make  clear.  Although  the  microscope  has  been  brought  to  a 
degree  of  perfection  hardly  to  be  improved,  there  are  still  forms  of 
life  which  are  beyond  its  power.  It  was  thought  until  recently 
that  bacteria  were  the  smallest  forms  of  life,  but  the  researches  of 
Dr.  Koch  and  others  have  brought  to  light  that  there  are  still 
smaller  organisms  which  are  the  probable  causes  of  maladies  such 
as  Foot  and  Mouth  disease.  Horse  Sickness  and  Rinderpest. 

However,  there  are  so  many  characteristics  of  plant  life  in 
bacteria,  that  they  are  properly  assigned  to  the  vegetable  kingdom. 
They  resemble  in  many  ways  the  higher  forms  of  microscopical 
plant  life,  viz.:  molds  and  yeasts  which  are  classed  as  fungi,  but 
in  size  they  are  very  much  smaller.  Bacteria  multiply  by  fission 
or  division,  from  which  characteristic  they  are  termed  Schizomy- 
cetes.  The  division  takes  place  by  a  lengthening,  when  a  constric- 
tion takes  place  thus : 


:p   c=Z=d 


O  O  en  OD 

i  Z  3  "^ 


Fig.  18 


34  CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 

The  yeasts  multiply  by  budding  as  also  do  some  of  the  molds 
under  certain  conditions.  The  yeasts  are  termed  Blastomycetes? 
The  molds  naturally  grow  in  a  thread-like  manner,  spreading  out 
and  sending  up  fine  hair-like  tufts  or  hyphae,  hence  they  are  termed 
Hyhomycetes.  The  classification  of  bacteria  is  not  complete.  There 
are  various  forms  which  are  taken  as  types,  but  changes  often  take 
place  due  to  the  character  of  the  substances  in  which  they  are  found, 
which  cause  one  class  to  appear  very  like  another  class.  The  classi- 
fication as  we  have  it  is  based  upon  the  form,  size,  motility,  manner 
of  dividing,  formation  of  spores,  the  presence  of  flagella  or  hair- 
like propellers,  their  ability  to  resist  high  temperatures,  the  enzymes 
or  products  resulting  from  their  growth,  the  colors  formed  by  cer- 
tain kinds,  the  flavor  produced  by  others,  their  manner  of  growth 
on  certain  artificial  media  or  food  specially  prepared  for  them  and 
many  other  ways,  but  first  they  can  be  divided  into  three  classes 
with  reference  to  external  appearance. 


0'     C/  ,^\      y^^ 


O   O  O 

O  O'  v./,  ^ 

A  3  c 

Fig.  19 


\y 


A— Micrococcus  or  single  round  cells 
B — Bacillus  or  rod  form. 
C  -  Spirillum  or  spiral  form 

A  very  short  bacillus  is  often  termed  a  bacterium.  The  spirilla 
or  curved  forms  are  often  joined  together  to  form  a  spiral  and 
were  called  vibrios  in  Pasteur's  time.  There  are  very  great  differ- 
ences in  sizes  of  bacilli,  some  being  quite  short  and  thick,  others 
very  long  and  delicate,  and  vice  versa.  Some  have  square  ends, 
others  are  rounded. 

There  are  many  different  kinds  of  bacteria  which  resemble 
each  other  in  all  that  the  microscope  will  reveal,  and  their  identifi- 
cation depends  upon  their  behavior  under  various  conditions.  It 
is  a  fact  that  the  identification  of  very  few  bacteria  can  be  deter- 
mined by  the  microscope  alone,  but  after  observing  a  certain  form 
in  many  conditions,  its  identity  may  be  pretty  clearly  determined. 
Changes  in  temperature  while  growing;  cultivations  in  acid  or  al- 
kaline media;  cultivations  in  fluid  and  on  solid  media  may  give 
rise  to  varied  shapes,  colors  and  products,  which  may  be  noted 
and  the  character  of  the  organism  established. 

The  action  of  chemicals,  dyes,  salt  and  sugar  solutions  may 
cause  what  is  known  as  plasmolysis,  which  is  a  shrinking  of  the 
cell  membrane  and  the  granulation  of  the  protoplasm  or  contents 
of  the  cell.  Sometimes  the  cell  membrane  disappears  so  that  the 
bacillus  appears  as  a  row  of  little  round  balls. 


BACTERIA.— DESCRIPTION  AND   CLASSIFICATION. 


35 


One  fact  has  been  established  which  is  interesting  to  the  stu- 
dent of  evolution,  i.  e.,  one  kind  of  bacillus  never  develops  into, 
another  kind.  Like  springs  from  like,  just  as  in  the  higher  forms 
of  life.  If  there  are  hybrids  among  them  it  has  not  been  proven, 
but  there  is  some  evidence  of  this  in  disease  organisms,  particularly 
in  mammal  and  avian  tubercule  bacilli.  Bacteria  are  known  to 
change  completely  in  some  respects,  but  their  identity  is  not  lost. 
We  have  seen  certain  species  which  ordinarily  do  not  liquefy  gela- 
tin, suddenly  divide  into  two  classes,  one  of  which  will  ever  after- 
ward liquefy  gelatin,  and  vice  versa.  Proteus  Zenkeri  is  probably 
a  type  of  this  species. 


1^ 


/ 


«i**v;./ 


S 


3 


^,^y 


i>,iV  >i>Mt-^  vi?'^  \A 


47</    /^ 


Fig.  20 

Illustrations  of  the  manifold  variety  in  size  and  form  of  different  bacteria. 
Except  A4  and  A5  all  the  above  illustrations  are  representations  of  equally  magni- 
fied bacteria  from  a  single  drop  of  pvitrescent  blood  (after  P.  Baumgarten)  x  950. 

A-1  Cocci  (micrococcus)  of  various  sizes. 

2  Diplococci  of  various  sizes. 

3  Streptococci  of  various  sizes. 

4  Micrococcus  tetragonus  (from  pure  culture)  magnified  950. 

5  Sarcina  ventriculi,  magnified  700 

6  Staphylococci. 

B-1,  2,  4  Separate  long  rods  of  various  lengths  and  breadths. 
3  Short  rods,  partly  of  biscuit  form. 

5  Chains  composed  of  either  short  or  long  rods. 

6  Ivong  threads. 


36  CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 

The  illustration  in  Fig.  20  gives  a  good  idea  of  the  appearance 
of  different  types  as  they  appear  under  the  microscope. 

The  manner  of  vegetation  or  multiplication  is  as  follows : 

The  Coccus  vegetates  by  becoming  longer,  constriction  follows 
and  finally  complete  separation. 

When  they  remain  united  in  twos  they  are  named  Diplococci. 

When  they  divide  in  two  directions  to  make  fours,  they  are 
named  Tetragoni. 

When  the)^  remain  united  forming  chains  they  are  named 
Streptococci. 

When  they  form  bunches  resembling  grapes  they  are  named 
Staphylococci. 

When  they  divide  in  three  directions  making  weight  cells  and 
remain  united  in  bundles  they  are  named  Sarcinci. 

The  rod  forms  may  lengthen,  divide  and  separate,  or  may 
form  pairs  or  chains  resembling  sausages.  These  chains  are  easily 
broken  up  by  agitation  so  that  they  appear  more  frequently  in  the 
field  of  view  under  the  microscope  in  all  three  forms. 

LI^E   HISTORY  OF   BACTERIA. 

Bacteria  are  present  almost  everywhere,  in  the  ground,  jnjhe 
air,  clinging  to  dust  and  floating  matter,  and  in  water.  They  find 
their  way  into  living  bodies  and  plants  and  are  most  numerous 
.where  there  is  decomposition  of  organic  matter.  The  air  in  mid- 
ocean  is  free  from  them,  because  all  suspended  particles  are  de- 
posited in  the  water  and  the  air  is  washed  until  it  is  pure.  The  air 
at  high  altitudes  is  almost  free  from  bacteria  and  the  soil  at  the 
depth  of  twelve  feet  also.  Water  from  artesian  wells  is  almost 
free,  and  whatever  contamination  it  has  is  due  to  the  deposit  of 
germ  life  from  the  surface.  The  air  that  is  exhaled  from  the 
lungs  is  free;  no  matter  how  many  thousands  of  bacteria  are  in- 
haled, they  are  caught  by  the  hairs  and  mucous  in  the  air  passages 
and  cast  out  or  eventually  destroyed,  except  where  disease  is  con- 
tracted. The  origin  of  bacteria  is  not  known,  but  is  shrouded  in 
the  mystery  of  creation.  There  is  evidence  that  new  species  are 
created,  although  it  cannot  be  stated  as  a  positive  fact.  New  dis- 
eases make  their  appearance  and  cases  of  spoilage  in  food  products 
occur  which  seem  to  be  new.  The_greBt  majority  of  bacteria  are 
harmless  to  man,  indeed  are  very  necessary  and  indispensable  as 
decomposing  agents  of  dead  organic  matter.  Through  their  in- 
strumentality, obnoxious  accumulations  are  reduced  to  elementary 
forms  capable  of  building  up  new  life,  both  animal  and  vegetable. 

There  is  another  class  called  pathogenic  bacteria  which  are  in- 
strumental  in  the  destruction  of  living  animals,  including  man.  This 
class  is  to  the  bacterial  flora  what  the  poisonous  plants  and  weeds 
are  to  the  higher  forms  in  the  vegetable  kingdom,  and  like  these 


BACTERIA.— DESCRIPTION  AND  CLASSIFICATION.  37 

are  in  the  minority.  Bacteria,  as  we  have  stated,  are  almost  uni- 
versally distributed,  but  are  not  always  in  the  full  vegetating  form 
as  we  see  them  under  the  microscope.  They  become  dried  up,  or 
in  spore  form  are  wafted  through  the  air  or  are  carried  by  water 
until  they  are  lodged  upon  certain  kinds  of  organic  material  which 
furnish  them  the  necessary  elements  for  growth,  which  is  termed 
vegetation.  This  is  a  multiplication  which  continues  until  certain 
conditions  arise,  such  as  change  of  temperature  or  chemical  com- 
position, due  to  their  own  action  or  the  products  formed  by  other 
kinds  of  bacteria  vegetating  at  the  same  time  with  them,  or  by  con- 
ditions arising  from  natural  causes,  when  they  either  perish  or 
pass  into  a  resting  or  dormant  state.  The  resting  state  is  charac- 
terized by  a  drying  up  of  the  cell  membrane  or  the  formation  of 
spores.  While  it  is  probable  that  nearly  all  bacteria  give  rise  to 
spores  of  some  kind,  this  has  not  been  demonstrated  as  a  fact,  be- 
cause the  conditions  under  which  we  cultivate  them  for  study  and 
observation  are  not  always  as  favorable  as  the  conditions  under 
which  they  grow  naturally;  then,  again,  the  extreme  minuteness  of 
many  forms  prevents  the  close  examination  necessary  to  establish  a 
complete  life  history.  There  is  evidence  that  spore  formation  may 
go  on  in  a  field  far  beyond  the  powxr  of  our  best  microscopes. 
The  phenomenon  of  spore  formation  is  observed,  however,  in  the 
life  history  of  a  large  number  of  bacteria,  and  the  formation  and 
liberation  of  spores  in  many  cases  can  be  watched  with  interest  in 
the  hanging  drop  cultures.  The  formation  of  spores  is  not  always' 
due  to  the  causes  assigned  above,  viz.,  the  exhausting  of  the  food 
supply,  etc.,  for  it  frequently  occurs  when  the  nourishment  is  most 
favorable  for  natural  vegetation  or  multiplication.  We  must  make 
a  clear  distinction  between  spore  formation  and  vegetation,  the 
spores  correspond  to  the  seed  in  higher  plant  life  and  are  formed 
for  the  perpetuation  of  the  species,  while  the  vegetation  is  a  multi- 
plication, not  by  seed  formation  but  by  division,  and  may  go  on 
almost  indefinitely,  if  the  bacteria  are  constantly  transplanted  into 
fresh  nutrient  material.  (There  are  exceptions  to  this  however.) 
The  pathogenic  bacteria  do  not  naturally  show  spore  formation,! 
because  the  living  body  supplies  them  constantly  with  fresh  ma- 
terial for  multiplication.  Some  of  the  pathogenic  bacteria  when 
grown  artificially  in  the  laboratory  on  nutrient  media,  do  give 
rise  to  spores,  showing  their  relationship  to  the  ordinary  non- , 
pathogenic  bacteria.  Anthrax  and  Tetanus  are  examples  of  this  \ 
kind. 

Fig.   21.     Sporulatlon 

a — First  stage  showing  granules,     b — Incomplete  spore,     c — Developed  spore. 

(After  Novy.) 


38  CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 

Nearly  all  text-books  speak  of  two  kinds  of  spore  formation, 
viz.,  endospores  and  arthrospores,  from  a  theory  advanced  by  De 
Bary.  The  endospore  is  always  formed  within  the  cell.  The  arth- 
rospore  formation  is  supposed  to  be  a  complete  thickening  of  the 

t  r  ,/^ 

Plate  4.     Anaerobic  Pea  Bacillus 

Photomicrograph  of  the  Spore-bearing  rods  of  tHfe  Anaerobic  Pea  Bacillus  found  in  a  can  of  swelled  peas 
The  spores  are  terminal  and  greatly  resemble  Bacillus  tetanus.     Magnified  1,000  diameters. 

cell  membrane  which  contracts  so  that  the  cell  thus  becomes  a 
spore.  The  arthrospore  theory,  however,  is  not  well  founded  be- 
cause the  actual  observance  of  this  phenomenon  is  wanting.  We 
are  only  certain  of  endospore  formation.  The  formation  of  spores 
is  thus  observed :  The  w^hole  bacillus  is  first  seen  as  a  colorless, 
homogeneous  cell,  showing  no  bright  spots.  When  it  advances  to 
the  state  of  spore  formation,  fine  granules  can  be  detected  scat- 
tered throughout  the  cell,  some  very  small,  others  larger  and  ir- 
regular, one  bright  spot  continues  to  grow  larger  and  brighter  and 
the  other  granules  may_  probably  be  absorbed  by  it — the  bright 
spot,  at  first  irregular,  now  begins  to  assume  definite  shape,  either 
round  or  ellipsoidal,  with  a  dark  line  forming  around  it  which 
seems  to  grow  thicker,  forming  a  wall  which  seems  to  enclose  all 
the  contents  or  protoplasm  of  the  cell,  or  the  protoplasm  may  go 
to  build  up  the  spore  wall,  which  is  probably  the  case.  The  old 
cell  is  now  merely  a  shell  containing  the  spore  and  may  soften  and 
disappear  in  the  surrounding  fluid,  leaving  the  bright  spore  in  a 
free  state.  In  some  cases  the  cell  remains  together  with  the  spore 
and  may  not  dissolve.  This  complete  process  may  occupy  several 
days,  but  is  often  accomplished  in  a  much  shorter  time. 


BACTERIA.— DESCRIPTION  AND  CLASSIFICATION.  39 

Ordinarily  one  spore  develops  within  a  single  bacillus,  but  A. 
Koch  has  mentioned  that  Bacillus  Inflatus  has  two;  this  is  im- 
probable. Not  every  bacillus  gives  rise  to  spores — it  sometimes  is 
observed  that  a  whole  chain  of  bacilli  will  be  seen  with  spores  ex- 
cepting one  or  two  which  seem  barren. 


) 


f  t  f       .wi,^       -** 


Fig.  22 


Bacillus  Inflatus — a,  b,  e,  cells  of  Clostridium  form  one  elongated  cylindrical  en- 
dospore.  c,  d,  f,  g,  cells  with  two  spores  of  unequal  size.  Magnified  2,100. 
(After  A.  Koch.)  Spirillum  Endoparagogicum — b,  vegetative  cells,  a,  two  cells, 
one  with  two  and  the  other  with  three  endospores.  (After  Sorokin.)  Bacillus 
Tumescens — Chain  of  seven  cells,  six  of  which  have  developed  one  spore  each, 
while  the  middle  cell  has  remained  barren.   It  is  granular.  X  1,100.    (After  A,  Koch) 


Plate  5 

Photomicrograph  of  rods  containing  terminal  spores,  barren  rods  and  free  spores. 

Spores  develop  in  a  certain  position  in  the  bacilli  of  the  same 
kind,  which  is  a  guide  to  the  student  for  identification.  When  a 
single  spore  develops  in  the  end  it  is  named  a  terminal  spore,  when 
in  the  middle  of  the  cell  it  is  called  a  median  spore,  when  in  a  posi- 
tion between  these  two  it  is  called  an  intermediate  spore.  During 
spore  formation  the  form  of  the  mother  cell  may  remain  unchang- 
ed, but  more  of  swelling  takes  place  at  the  point  of  spore  forma- 
tion, so  that  the  bacillus  represents  a  drum  stick,  club,  or  nail 
head,  if  the  spore  is  terminal  and  may  resemble  a  spindle  or  lemon, 
if  the  spore  is  median  or  intermediate,  this  form  is  designated  as 
a  Clostridium. 


40  CANNING    AND    PRESERVING    OP    FOOD    PRODUCTS. 

The  size  of  spores  varies ;  they  are  usually  oval  or  ellipsoidal 
I/*  to  3/^  in  length  (*/x  =1/25,000  of  an  inch)  by  5/>t  to  i/j-  in  breadth, 
although  we  have  reason  to  believe  there  are  some  very  much 
smaller. 


Fig.  23 

Vibrio  Rugula — Seven  rods  with  a  terminal  spore.  Magnified  1,020.  Clostridium 
Butyricum — a,  b,  vegetative  cells;  d,  beginning  of  spore  formation;  c,  e,  progress; 
f ,  h,  completion  ;  a,  f,  contain  granular  stained  blue  by  iodine  ;  h,  sustained  by 
iodine  ;  g,  cell  with  two  spores.     X  1020.     (After  Prazmowski. ) 

As  we  have  stated  before,  the  formation  of  spores  is  the  means 
of  perpetuating  the  species,  consequently  a  number  of  bacteria  are 
known  to  give  rise  to  spores  whenever  the  conditions  are  such  that 
the  bacilli  cannot  continue  in  the  vegetating  state.  In  order  that 
the  spore  may  be  able  to  live  through  great  changes  in  tempera- 
ture, the  cell  wall  is  thick  and  not  easily  penetrated  by  heat  or  dyes, 
consequently  in  the  ordinary  staining  methods,  the  spores  present 
their  oil-like  refractory  appearance,  while  the  surroundings  are  per- 
fectly stained. 

On  account  of  the  heat-resisting  power  of  spores,  the  study  of 
this  phenomenon  is  interesting  to  the  canner.  At  one  time  it  was 
believed  that  the  bacilli  as  well  as  the  spores  could  be  destroyed  by 
212  degrees  F.,  steam  heat,  in  fifteen  minutes,  and  no  less  an  au- 
thority than  Koch  fell  a  victim  to  this  theory,  which  E.  von  Es- 
march  overthrew.  The  spores  of  some  bacteria  were  found  to  be 
able  to  sustain  life  after  continuous  boiling  for  six  to  ten  hours. 
The  same  spores  were  destroyed,  however,  by  a  temperature  of 
250  degrees  for  fifteen  minutes,  steam  heat  directly  applied.  This 
extreme  heat-resisting  power  led  some  famous  bacteriologists  into 
error.  Prominent  among  them  was  Von  Liebig,  who  built  up  a 
theory  of  spontaneous  generation,  founding  it  on  the  life  which 
spontaneously  destroyed  certain  infusions  such  as  meat,  milk  and 
hay,  after  all  life  (as  he  thought)  had  been  killed  by  boiling  heat. 
Pasteur  and  Tyndall  did  not  follow  this  theory,  but  labored  to  dis- 
cover the  cause  of  their  failure  to  preserve  certain  infusions.  After 
numerous  experiments  they  were  able  to  state  positively  that  there 
were  forms  of  life  which  could  live  through  the  boiling  point;  so 
the  system  of  discontinuous  heating  was  discovered  by  Tyndall  and 


*The  Greek  letter  m   is  an  abbreviation  for  the  Greek  word  micron,  which 
means  small  and  is  equivalent  to  2  oio  0  ^^  ^^  inch. 


BACTERIA.— DESCRIPTION  AND  CLASSIFICATION.  41 

this  method  of  steriHzation  is  still  used  to  this  day  as  a  means  of 
sterilizing  cer^tain  materials  which  are  altered  by  the  employment 
of  high  temperatures. 

The  theory  was  built  upon  the  fact  that  the  tender,  vegetating 
forms  of  life  were  easily  destroyed  by  temperatures  as  low  as  i6o 
degrees  F.,  consequently  after  heating  once  the  first  day,  Tyndall 
allowed  the  infusions  to  cool,  and  stand  long  enough  for  the  spores 
to  begin  to  develop  into  bacilli,  when  he  again  subjected  them  to  a 
second  heating,  and  repeated  the  process  three  times,  by  which  he 
killed  all,  the  spores  having  all  started  to  germinate.  While  this 
system  is  useful  for  the  sterilization  of  some  infusions,  it  cannot 
be  declared  infallible,  since  only  the  aerobic  bacteria  (i.  e.,  bacteria 
which  grow  in  the  presence  of  air),  would  develop  from  their 
spores  during  the  intervals  between  the  heatings.  The  spores  of 
the  anaerobic  bacteria  would  not  germinate  unless  the  process  were 
repeated  in  a  condition  where  air  was  expelled.  This  would  re- 
quire a  number  of  heatings,  some  after  exposure  to  air  for  the 
spores  of  aerobic  bacteria  to  germinate  and  some  after  the  exclu- 
sion of  air  for  the  spores  of  the  anaerobic  bacteria  to  germinate. 
For  ordinary  purposes,  however,  the  temperature  of  250  degrees 
F.  was  found  sufficient  to  destroy  all  life  in  material  which  was 
not  altered  by  the  heat. 

Under  ordinary  conditions,  the  spores  of  bacteria  will  live  for 
a  number  of  years.  Cold  does  not  seem  to  destroy  the  spores 
and  only  a  few  antiseptics  will  kill  them.  Pressure  of  great  power 
does  not  destroy  them  nor  have  electricity  nor  the  X-rays  proved 
successful  destructive  agents.  Radium  has  no  devitalizing  power, 
as  demonstrated  by  Prescott.  Carbolic  acid,  bichloride  of  mercury, 
and  hydrocyanic  acid  will  destroy  them  in  a  few  minutes,  but  ordi- 
nary antiseptics  in  such  proportions  as  are  commonly  used  for  the 
preserving  of  certain  condiments,  do  not  destroy  the  spores,  but 
produce  conditions  which  are  unfavorable  for  their  vegetating  into 
full-grown  bacilli. 

THB  SPORB  IS  THE  LIPB  SBBD  of  any  given  species, 
and  if  all  moisture  is  absorbed  from  its  surroundings,  it  will  dry 
up,  the  membrane  around  it  will  harden,  and  it  may  cling  to  dust 
or  floating  particles  in  the  air,  and  be  wafted  here  and  there  by 
currents  of  air  until  it  falls  into  a  substance  suitable  for  its  germi- 
nation, or  it  may  die,  although  it  has  been  know^n  to  remain  alive 
and  have  power  to  germinate  after  many  years  of  dormancy. 

When  it  falls  into  a  suitable  medium  for  its  germination,  the 
spore-wall  softens  and  a  considerable  amount  of  moisture  is  ab- 
sorbed, which  results  in  the  development  of  a  living  cell ;  this  will 
lengthen  and  divide,  remain  attached  or  become  free,  until  the  con- 
ditions are  reached  for  the  cells  to  form  spores  again.     Spores  do 


42 


CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 


not  multiply,  they  simply  furnish  the  life  for  one  new  cell,  which 
will  multiply. 

THE  GERMINATION  Of  SPORES  is  different  in  many 
cases,  although  it  is  probable  that  spores  of  a  given  bacillus  always 
germinate  in  the  same  manner.  The  observation  of  spores  germi- 
nating is  a  tedious  proceeding,  requiring  much  time  and  careful 
preparation.  It  is  usually  observed  in  the  hanging  drop  culture, 
which  is  made  by  placing  a  drop  of  nutrient  material  on  a  cover- 
glass  and  inoculating  this  with  a  species  which  has  formed  spores 
in  some  other  medium.  The  cover-glass  is  then  inverted  on  a  slide 
with  a  hollow-ground  cell  in  the  center  so  that  the  drop  will  hang 
without  touching  the  glass,  the  cover-glass  being  sealed  all  around 
by  vaseline  to  prevent  evaporation,  thus : 


Fig,  24.     Hanging  Drop  Culture 

H — Hanging  Drop. 

C — Cover  glass  over  the  cell. 

V — Vaseline  holding  cover  glass  over  slide  S. 


The  edge  of  the  drop  is  found  with  the  low  power  objective 
first,  and  then  a  drop  of  cedar  oil  is  placed  on  the  top  of  the  cover- 
glass  and  the  1-12  oil  immersion  lens  is  brought  down  into  focus. 
The  first  sign  of  spore  germination  will  be  a  glistening  of  the 
spore,  which  will  be  seen  to  swell  and  lengthen,  grow  less  bright, 
until  a  homogeneous  cell  is  formed  showing  very  little  or  no  re- 
fraction. 

The  germination  is  accomplished  in  several  ways. 

Probably  the  most  common  method  of  spore  germination  is 
the  growth  of  the  bacillus  from  one  end.  The  end  appears  to  open 
and  the  young  cell  pushes  out  in  the  long  axis  of  the  spore.  An- 
other method  is  the  opening  of  the  spore  at  the  sides,  when  the 
spore  seems  to  split  in  halves,  letting  the  young  cell  out  in  a  right 
angle  to  the  long  axis  of  the  spore. 

Another  method  is  the  opening  of  the  spore  wall  on  one  side 
through  which  the  young  cell  emerges  in  a  bent  form,  the  middle 
coming  out  first  and  then  the  ends,  causing  the  young  cell  to  look 
like  a  magnet  or  horse-shoe. 


BACTERIA.— DESCRIPTION  AND  CLASSIFICATION.  43 

Another  method  of  g-ermination  is  the  swelhng  of  the  spore 
by  a  gradual  elongation  of  the  spore,  which  seems  to  absorb  mois- 
ture, increasing  in  protoplasm  until  a  fully  developed  cell  is  born, 
able  to  multiply  in  the  regular  manner. 

^  :b  ^ 

•   i    §    0      0  O    O  ^  (/</  43   0    0  O    d^r. 

0  1^ 

Fig.  25 

A — Lengthening  of  the  spore. 
B — Bacillus  growing  out  of  the  end  of  the  spore. 
C — Bacillus  growing  out  of  the  side  of  the  spore. 

D — Bacillus  growing  out  of  the  divided  spore  and  in  in  horse  shoe  shape  at 
the  side. 

The  study  of  spores  is  most  interesting  to  the  manufacturer 
of  food  products,  for  the  reason  that  they  are  very  resistant  to 
heat,  which  is  usually  employed  to  sterilize  all  canned  goods  and 
many  other  kinds  of  goods  as  well.  There  are  some  varieties  of 
spores  which  live  through  continuous  boiling  for  five  hours  and 
more,  but  are  killed  at  250°  F.  by  directly  applied  steam  heat,  in 
about  fifteen  minutes.  Now,  this  heat  must  come  directly  onto  the 
spores,  so  the  larger  and  denser  the  volume,  the  longer  it  takes  to 
heat  it  to  the  center.  '  Various  liquids,  such  as  soups,  are  canned, 
^^'hich  convey  the  heat  better  than  heavier  materials,  such  as  corn, 
peas,  meats,  etc.,  and  to  destroy  the  spores  of  certain  classes  of 
bacteria  the  temperature  of  250° F.  must  reach  the  center  of  the 
package  and  be  maintained  for  about  fifteen  minutes.  For  experi- 
mental tests,  there  are  made  especially  for  this  purpose  self-regis- 
tering thermometers  which  fit  into  the  can  and  remain  in  the  center. 
When  the  temperature  reaches  250°  F.  the  mercury  does  not  drop 
on  cooling" — owing  to  a  constriction  in  the  tube  which  holds  it — 
until  it  is  shaken  down  by  gentle  tapping. 

Valuable  knowledge  may  be  gained  by  the  canner  from  per- 
sonal experiment  with  this  device  in  his  sterilizing  processes.  By 
noting  how  many  minutes  it  requires  to  reach  the  proper  tempera- 
ture after  the  retort  thermometer  indicates  the  right  temperature 
on  the  outside,  he  can  know  just  how  long  he  must  process  his 
goods  to  destroy  the  spores  of  such  bacteria  as  are  known  to  infest 
the  particular  product  which  he  is  canning.  The  canner  must  first 
study  just  what  bacteria  are  continually  present  in  the  particular 
products  he  is  manufacturing;  this  is  found  out  by  cultivation  on 
nutrient  media  similar  to  those  products.  T.ater  we  will  explain 
how  to  make  these  cultivations  so  that  all  kinds  of  germs  may  be 
isolated  and  identified,  when  grown  by  themselves,  and  experiments 


44  CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 

made  by  inoculating  sterile  cans  and  subjecting  the  bacteria  to  vari- 
ous temperatures  in  order  to  learn  their  resisting  power  to  heat, 
etc. 

NATURE  OF  BACTERIA. 

COMPOSITION.  Water  makes  up  a  large  per  cent,  of  the 
composition  of  bacteria  and  is  calculated  to  be  from  60  to  85  per 
cent. ;  fats,  from  i  to  40  per  cent. ;  proteins,  10  to  15  per  cent. ;  min- 
eral compounds,  i  per  cent. ;  sometimes  cellulose  and  granulose  are 
present,  particularly  in  the  carbohydrate  species.  All  bacteria  con- 
tain one  or  more  soluble  ferments  which  are  compounds  capable 
of  producing  fermentation,  and  are  called  enzymes.  The  class  of 
bacteria  which  produces  diseases  in  man  and  animals  produces 
poisons  called  ptomaines  and  toxins,  which  may  be  extracted.  From 
the  non-pathogenic  bacteria  also  the  enzymes  may  be  extracted, 
some  of  which  are  used  in  producing  desired  fermentations.  Heat 
usually  destroys  these  enzymes  as  well  as  a  great  many  toxins  from 
pathogenic  bacteria. 

The  average  composition  of  bacteria  is  estimated  at  85  per 
cent,  water  and  15  per  cent,  dry  matter  (by  Kappes).  The  dry  mat- 
ter is  made  up  as  follows : 

Per  cent. 

Etherial  extract  (fat.  etc.) 4.8 

Albumen 71.2 

Ash 13-5 

Undetermined  matter   io»5 

There  is  a  very  large  per  cent,  of  nitrogen  ni  bacteria,  far  more 
than  in  the  higher  vegetable  orders,  and  carbon  enters  largely  in- 
to the  composition  of  the  protoplasm.  The  bacterial  cells  are  de- 
void of  chlorophyll — (the  green  coloring  matter  of  the  higher 
vegetable  kingdom) — consequently,  they  cannot  obtain  the  carbon, 
as  do  the  higher  plants,  from  carlDonic  acid  gas,  but  are  dependent 
upon  carbon  compounds.  Sugar  furnishes  carbon,  also  other  car- 
bohydrates and  fats,  proteins,  and  likewise  organic  compounds,  such 
as  glycerin,  tartaric  and  lactic  acids. 

The  nitrogen  of  the  air  cannot  be  utilized  by  bacteria  (one 
class  excepted),  consequently  they  are  dependent  upon  nitrogenous 
compounds  for  their  supply.  Animal  and  vegetable  matter  is  al- 
ways accessible,  the  proteins  of  wdiich  furnish  the  nitrogen.  Chem- 
ical compounds  and  acids  can  also  be  utilized. 

.  The  hydrogen  is  obtained  from  the  same  sources  as  the  carbon 
and  nitrogen,  but  the  oxygen  may  be  obtained  from  the  atmos- 
phere or  from  compounds,  according  to  the  kinds  of  bacteria  and 
their  environments. 

Some  bacteria  thrive  well  in  media  which  are  acid;  others 
thrive  better  in  alkaline  media. 


BACTERIA.— DESCRIPTION  AND  CLASSIFICATION.  45 

The  chemical  composition  of  bacteria,  therefore,  depends  to  a 
great  extent  upon  the  nature  of  the  substance  upon  which  they  are 
thriving.  Certain  bacteria  may  grow  luxuriantly  in  an  acid  medium 
such  as  tomatoes  and  fruit  juices  and  may  remain  dormant  or 
die  in  an  alkaline  medium.  Then,  again,  other  kinds  of. bacteria 
which  grow  well  on  an  alkaline  medium  will  remain  dormant  or 
die  in  an  acid  medium.  To  this  class  the  majority  of  bacteria  be- 
long. This  difference  in  the  nature  of  bacteria  will  throw  some 
light  on  the  different  temperatures  employed  in  sterilization,  the 
character  of  the  bacteria  being  determined  by  the  degree  of  acidity 
of  the  material. 

BACTE:rIA  AND  THKIR  SUPPLY  OF  OXYGEN. 

Many  kinds  of  bacteria  obtain  the  oxygen  so  necessary  for  the 
process  of  multiplication  from  the  air,  and  if  the  air  is  cut  off  they 
either  remain  dormant  or  die — these  are  called  aerobic;  others  can- 
not use  the  oxygen  of  the  air,  so  they  obtain  their  supply  from  or- 
ganic compounds,  such  as  the  proteins  and  carbohydrates;  these 
are  called  anaerobic.  There  are  others  which  accommodate  them- 
selves to  whatever  condition  in  which  they  may  be  placed,  if  aerobic 
by  nature  they  will  still  grow  in  an  anaerobic  state  and  are  called 
facultative  anaerobes;  or  if  anaerobic  by  nature  and  grow  in  an 
aerobic  state  they  are  called  facultative  aerobes. 

Nearly  all  bacteria  found  in  improperly  sterilized  hermetically 
sealed  packages  are  either  anaerobic  or  facultative  anaerobic.  This 
latter  class  sometimes  causes  more  violent  fermentation  when  forc- 
ed to  grow  in  the  absence  of  free  oxygen  than  when  growing  nat- 
urally; being  deprived  of  free  oxygen  the  tearing  down  of  organic 
compounds  is  accomplished  with  great  rapidity  to  supply  the  re- 
quired oxygen,  while  the  actual  multiplication  is  lessened.  This 
fact  is  interesting  to  canners,  as  it  accounts  for  the  rapid  spoilage 
of  goods  which  have  been  improperly  sterilized.  Here  the  fermen- 
tation is  much  more  violent  and  rapid  than  in  the  packages  where 
there  is  a  perceptible  leak  through  which  the  oxygen  from  the  air 
passes.  It  is  curious  that  sometimes  the  product  will  be  found 
perfectly  sweet  at  the  bottom  of  a  can  which  has  a  large  leak  in 
the  top,  while  the  whole  surface  is  covered  with  molds,  yeasts  and 
bacteria  of  various  kinds.  In  this  case  the  evolution  of  gas  is  not 
as  great  as  when  the  can  is  undergoing  chemical  changes  in  the 
absence  of  atmospheric  oxygen. 

To  the  facultative  anaerobes  a  large  per  cent,  of  losses  in  can- 
ned goods  is  due.  The  anaerobic  bacteria,  however,  cause  spoilage 
in  many  cases  where  the  others  are  destroyed,  because  they  belong 
to  the  soil  and  are  spore -bearing  and  have  the  power  to  withstand 
very  high  temperatures  and  afterward  develop.  All  anaerobes 
known,  except  possibly  one  species,  are  bacilli,  that  is,  rod-shaped. 


46  CANNING    AND    PRESERVING    OP    POOD    PRODUCTS. 


Bacterium  Phosphorescens,  Fischer 


PHOTOBACTERIUM     PHOSPHORESCENS. 

Origin. — It  is  found  on  dead  seafish,  oysters,  etc.  Meat  in  butcher 
shops  may  be  contaminated  from  these. 

Form. — Short,  thick  bacillus,  having  rounded  ends;  almost  a  coccus 
sometimes.  Usually  found  in  pairs,  but  may  form  threads;  involution 
forms  soon  develop. 

Motility. — It  is  not  motile. 

Sporulntion. — Has  not  been  observed. 

Anilin  Dyes. — Stain  readily,  as  does  also  Gram's  method. 

Growth. — The  growth  is  moderately  rapid.  Cultures  show  a  marked 
bluish-green  phosphorescence  in  the  dark. 

Gelatin  Plates. — The  colonies  are  small,  white  and  glistening,  and 
do  not  liquefy ;  they  have  a  sharp,  irregular  border ;  are  granular,  and 
show  several  concentric  rings. 

Stah  Culture. — This  shows  a  slight  granular  growth  along  the  line 
of  inoculation.  Is  most  abundant  on  the  surface,  forming  there  a  thin 
grayish  white  covering.     The  gelatin  is  colored  a  yellowish  brown. 

Streak  Culture. — On  agar,  potato,  etc.,  the  growth  is  limited  to  the 
line  of  inoculation.  The  growth  is  very  good  on  fish,  beef,  bread,  fats, 
etc. 

Oxygen  Requirements. — It  is  a  facultative  anaerobe.  The  produc- 
tion of  light  depending  upon  the  presence  of  oxygen,  it  is  most  marked  on 
the  surface  growths.  The  intensity  of  the  light  may  diminish,  or  may 
even  become  lost  (attenuation),  but  may  be  restored  by  growth  on  suit- 
able media,  such  as  fish. 

Temperature. — Will  not  grow  in  the  incubator.     May  grow  at  o°  C. 

Behavior  to  Gelatin. — Does  not  liquefy.     It  may  ferment  sugar. 

Pathogenesis. — It  has  no  effect  on  animals.  One  species  is  said  to 
produce  a  disease  in  certain  Crustacea. 


BACTERIA.— DESCRIPTION  AND   CLASSIFICATION. 


47 


INFUENCE:   of   EI/ECTRICITY   on    BACTERIA. 

Cohn  experimented  with  electricity  generated  by  two  cells, 
passing  the  current  through  a  fermentable  substance  where  bacteria 
were  present  and  found  that  they  w^ere  not  killed,  but  that  changes 
were  produced  which  made  the  medium  unfit  for  bacteriological 
development.  Later  a  stronger  current  of  electricity  was  tried  by 
other  investigators  and  some  forms  were  killed,  but  the  resistant 
forms  found  in  milk  were  not  affected,  which  dashed  the  hopes  of 
those  seeking  a  speedy  method  of  sterilizing  milk.  D'Arsonval 
and  Charrin  used  a  current  of  10,000  volts  on  a  certain  species  of 
germ  found  in  pus,  but  only  a  decrease  in  virulence  was  observed. 

Electricity,  however,  is  used  in  the  manufacture  of  wine  and 
cognac  for  maturing  the  flavor  and  not  for  antiseptic  purposes.  A 
certain  mellow  flavor  is  produced  by  pouring  the  liquors  over  plates 
charged  with  electricity. 

The  results  of  these  experiments  proved  that  electricity  was 
not  practical  as  a  germicide,  but  that  certain  chemical  reactions 
were  produced  which  were  inimical  to  bacterial  growth.  If  salt 
were  present  in  the  current  it  would  be  either  decomposed  into  acid 
and  alkali  or  set  free,  chlorine  and  hypochlorites.  Sometimes  per- 
oxide of  hydrogen  and  ozone  w^ould  be  generated  by  the  electric  cur- 
rent in  sufficient  amounts  to  destroy  a  number  of  non-resistent 
forms.  Heat  also  is  generated  which  will  destroy  germs  of  the 
same  class. 

It  was  expected  that  the  X-rays  would  prove  to  be  of  value  as 
a  germicide,  but  many  experiments  have  resulted  negatively.  Like- 


CALIFOgg^^ 


Plate  6.     Bacillus  Phosphorescens 

Magnified  1,000  diameters. 


48  CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 

wise  it  has  been  demonstrated  that  Radium  does  not  destroy  bac- 
teria to  any  appreciable  extent. 

INFI.UI:NCE  of  TKMPltRATURE. 

The  subject  of  temperature  is  most  interesting  to  canners  and 
manufacturers  of  food  products  because  it  opens  up  a  way  of  suc- 
cessfully destroying  the  scavengers  which  constantly  menace  those 
products. 

Bacteria  grow  best  between  the  temperatures  of  70°  F.  and 
ioo°F.,  but  are  able  to  live  through  great  changes  which  seem 
marvelous  to  those  who  have  not  had  experience  and  suffered  losses 
through  their  ravages. 

There  has  been  discovered  one  species  of  bacteria  which  multi- 
plies at  32°F.  It  was  discovered  in  1887  by  J.  Forster  growing  on 
the  surface  of  salt  water  fish,  a  phosphorescent  variety.  Later  it 
was  discovered  by  B.  Fischer  that  the  soil  and  also  sea  water  con- 
tained many  varieties  which  could  grow  at  32°F.  A  great  num- 
ber of  these  hardy  varieties  grow  in  milk  and  drain  water. 

Experimenters  have  tried  various  temperatures  as  low  as  250° 
below  zero,  also  in  solidified  oxygen  for  many  hours,  and  some  va- 
rieties lived  through  the  tests.  Severe  cold  is  germicidal  to  many 
species. 

This  is  interesting  in  connection  with  cold  storage  and  ac- 
counts for  some  peculiar  changes  we  have  witnessed.  In  a  general 
way  it  can  be  stated  that  the  freezing  point  will  retard  decomposi- 
tion of  food  stuffs,  in  fact  33°  and  34° F.  will  keep  fruits  and  vege- 
tables very  well  for  a  long  time,  but  there  is  loss  in  flavor  from 
the  formation  of  CO2  (carbonic  acid  gas),  due  to  the  breaking  up 
of  small  quantities  of  sugar,  either  by  bacteria  or  the  cell  life  of 
the  fruit  itself. 

The  temperature  required  to  protect  meats  and  butter  is  con- 
siderably lower  than  freezing,  averaging  about  13^  to  io°F.,  but 
even  in  this  temperature  after  a  time  certain  changes  ma}^  be  noted 
which  are  not  due  to  bacterial  action,  (but  are  due  to  a  loss  of  vola- 
tile ethers  which  are  retained  by  hard  freezing.)  Commerically,  cold 
storage  is  a  good  method  of  carrying  over  food  stuffs  of  many 
kinds,  but  of  course  decomposition  will  set  in  quickly  after  they  are 
brought  into  warm  temperatures  for  the  reason  that  their  exposure 
to  germ-laden  atmosphere  has  invited  hosts  of  bacteria  which  will 
start  their  functions  when  brought  into  warmer  temperatures. 

It  is  my  belief  that  the  cold  storage  system  will  come  into 
favor  with  the  canner  and  preserver.  In  a  series  of  experiments 
recently  tried,  fruits  and  vegetables  kept  nicely  when  frozen  solid. 
Such  products  if  subjected  to  13'^F.  freeze  solid  and  retain  their 
flavor  fairly  well,  but  can  only  be  used  in  jams  and  sauces,  etc.. 


BACTERIA.—DBSCRIPTION  AND   CLASSIFICATION.  49 

owing  to  the  collapse  which  takes  place  when  thawed  out.  Even 
for  these  purposes,  the  system  is  advantageous,  especially  when 
overcrowded  with  raw  fruits  and  vegetables  the  canner  can  put 
into  cold  storage  his  surplus,  which  may  be  made  up  later  into 
marketable  products,  when  the  receipts  of  raw  materials  are  less. 

The  cost  of  building  a  cold  storage  plant  for  every  canner  is 
too  great  to  even  be  considered,  but  those  whose  factories  are  lo- 
cated within  a  short  distance  of  such  a  plant  can  take  advantage 
of  it.  Indeed  a  series  of  experiments  along  this  line  might  prove 
most  satisfactory. 

While  we  have  found  rare  species  of  bacteria  able  to  live  and 
multiply  in  freezing  temperatures,  it  is  interesting  to  note  that  there 
are  varieties  able  to  thrive  at  an  extreme  temperature  in  the  other 
direction.  These  bacteria  are  non-pathogenic,  that  is,  not  disease 
producing,  in  man  and  animal.  They  are  called  thermophilous, 
or  heat  loving  bacteria,  and  one  species  was  discovered  by  Miquel 
called  Bacillus  Thermophilus,  which  multiplies  at  I58°F.  When 
WQ  remember  that  this  temperature  kills  animal  life  and  coagulates 
egg  albumen  and  blood  serum,  we  are  impressed  with  this  remark- 
able fact.  This  is  an  aerobic  bacillus  about  i/x  in  thickness  and 
forms  threads  at  about  I40°F.  and  only  thrives  between  the  tem- 
peratures of  98°  and  i62°F.  This  bacillus  is  common  in  sewage 
and  is  found  in  the  alimentary  canal  of  man  and  animals. 

There  are  a  number  of  bacteria  which  grow  well  at  high  tem- 
peratures, most  of  which  are  found  in  the  soil,  in  sewage  water 
and  in  the  alimentary  tract.  During  the  extremely  hot  weather  of 
summer,  these  heat  loving  bacteria  grow  luxuriantly,  and  cause 
fermentation  wdiere  least  suspected. 

In  this  CGx^nection  I  wish  to  remind  our  readers  that  they  may 
have  seen  cans  of  improperly  sterilized  goods  fermenting  in  the 
center  of  a  pile  where  the  temperature  would  be  almost  scalding. 
I  have  seen  cans  of  corn  fermenting  with  so  much  heat  that  I  could 
scarcely  hold  a  can  in  my  hand.  There  has  been  very  little  investi- 
gation into  this  phenomenon,  but  some  of  these  bacteria  will  be  de- 
scribed and  their  resistance  explained.  There  are  certain  kinds  of 
mold  which  have  the  same  characteristics  as  the  thermophilous 
bacteria,  and  cause  great  loss,  especially  in  the  manufacture  of  cat- 
sups and  sauces  made  from  tomatoes.  Some  of  these  molds  are 
pathogenic  also,  and  are  associated  with  disease  in  the  lungs  of 
man  and  in  the  bronchial  tubes  and  throats  of  birds. 

Recently  we  examined  the  sputum  of  a  pneumonia  patient  and 
found  the  fungus  growing;  it  is  called  Aspergillus  Fumigatus  and 
will  be  described  later. 

There  have  been  discovered  in  the  hot  sulphur  springs  at 
Ilidze  in  Bosnia,  two  kinds  of  bacteria,  one  called  Bacterium  Lud- 
wigi,   which  developed  at   a  temperature   above   I22°F.,   and  the 


50  CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 


Aspergillus  Fumigatus,  Lichtheiiii 

Origin. — White  bread,  preserves,  catsup,  in  the  kings  and  air  pas- 
sages of  birds ;  met  with  in  man  also. 

Color. — Greenish  or  bluish-green  growth;  resembles  that  of  penicillium 
very  much. 

Mycelium. — Mycelial  threads  and  spores  are  smaller  than  those  of  A. 
niger. 

Fruit-Organs. — The  fruit  hyphae  are  club-shaped  and  covered  with 
sterigmae,  from  which  extend  rows  of  spores.  The  sterigmae  are  not 
divided.  The  spores  are  usually  colorless  and  from  2%  /x  to  3V2  /x  in  di- 
ameter. 

Grozvth. — Rapid.     Grows  best  on  bread. 

Bread  Flasks. — Low  growth;  at  first  bluish-green,  but  is  grayish-green 
when  old. 

Temperature. — Grows  best  at  37-40°  C.  Will  grow  at  ordinary 
temperature,  but  not  below  15°   C. 

Pathogenesis. — Death  was  produced  in  a  few  days  by  intravenous 
injections  of  millions  of  spores  in  rabbits  and  dogs.  Mycelia  were  found 
in  the  kidneys,  heart  and  other  muscles,  and  sometimes  in  the  liver. 

A  pneumonic  or  pseudo-tuberculous  disease  is  produced  by  the  in- 
halation of  the  spores  in  doves  and  other  birds.  Natural  affections  of  this 
kind  are  frequent  among  birds.  They  are  met  with  occasionally  in  horses 
and  in  cattle,  and  sometimes  in  man. 

In  mycoses  of  man,  the  lungs,  eyes,  ears  or  nose  are  subject  to  in- 
vasion. 

The  Japanese  utilize  the  growing  A.  Oryzae  as  a  diastatic  ferment. 
Rice  grains  are  converted  by  it  into  sugar  and  dextrin,  which  when  sub- 
jected to  fermentation  yields  the  national  drink,  Sake,  containing  about 
14%  of  alcohol.  Taka-diastase  is  a  ferment  which  is  derived  from  an  as- 
pergillus  similar  to  that  mentioned. 


BACTERIA.— DESCRIPTION  AND  CLASSIFICATION.  51 

Other  named  Bacillus  Capsulatus,  produced  endospores  which  lived 
through  a  heat  of  2i2°F.  for  four  hours  without  being  destroyed. 
We  have  called  attention  to  the  heat-resisting  powers  of  spore- 
bearing  bacteria  under  the  head  of  spores.  Among  these  are  sev- 
eral varieties  which  are  found  on  the  skin  of  potatoes  and  in  milk; 
also  one  variety  found  associated  wath  hay,  malt,  etc.  These  hardy 
varieties  found  on  potatoes  are  Mesentericus  Vulgatus,  Mesenter- 
icus  fuscus  and  Mesentericus  ruber,  the  spores  of  the  last  able  to 
live  through  six  to  ten  hours  boiling  at  2i2°F.     Bacillus  subtilis, 


Plate  7.     Aspergillus  Fumigatus 

Photomicrograph  of  unstained  mold  Aspergillus  Fumigatus,  which  sometimes  makes  its  appearance  on  food 
products,  such  as  preserves,  tomato  sauces,  etc.  It  is  pathogenic.  There  are  two  fruit  pods  full  of  conidia  near 
the  center.  Just  below  the  larger  pod  is  one  partially  disgorged.  Some  of  the  loose  spores  or  conidia  may  be 
seen  among  the  threads  of  the  mycelium.     Magnified  600  diameters. 

a  species  found  in  boiled  hay  and  malt  infusions,  gives  rise  to  very 
resistent  spores  and  gave  Prof.  Tyndall  so  much  trouble  in  his  ef- 
forts to  overthrow  the  theory  of  spontaneous  generation. 

INFLUENCE  OF  LIGHT  ON  BACTERIA. 

In  a  general  way  we  may  state  that  direct  sunlight  is  detri- 
mental to  the  growth  of  bacteria  and  is  germicidal  in  many  cases. 
The  effect  of  direct  rays  is  injurious  to  cultures  of  certain  species 
which  when  thus  exposed,  lose  their  power  to  vegetate  when  re- 
turned to  the  dark.  The  effect  of  sunlight  may  be  noted  in  many 
instances  by  its  peculiar  action  on  bacteria.     Certain  species  which 


52  CANNING    AND    PRESERVING    OF    POOD    PRODUCTS. 

are  actively  motile  due  to  flagella  (which  will  be  described  later), 
lose  their  power  to  move  and  gradually  weaken  and  die;  others 
which  are  called  Chromogenic  or  color-bearing  bacteria,  (see  sec- 
tion on  pigment — producing  bacteria),  lose  their  function  of  pro- 
ducing pigments;  the  pathogenic  bacteria  lose  their  power  to  pro- 
duce toxins  in  some  cases. 

It  is  the  ultra  violet,  violet,  and  blue  rays  of  sunlight  which 
are  so  germicidal;  the  green,  red  and  yellow  have  very  little  or  no 
injurious  effect  upon  bacteria.  F'or  extensive  literature  on  this 
phenomenon  the  reader  is  referred  to  Diendonne  (A.G.A.  iX,  405 
and  537). 

The  diffused  rays  of  sunlight  have  very  slight  disturbing  in- 
fluences on  bacteria;  likewise  arc  light  and  incandescent  influences 
may  be  observed. 

The  action  of  sunlight  may  produce  chemical  change  in  the 
medium  on  which  the  bacteria  are  thriving,  such  as  the  oxidation 
of  fats,  formic  acid  and  formaldehyde  and  peroxide  of  hydrogen 
may  be  formed,  which  will  be  germicidal.  In  this  connection  let 
me  say  that  these  compounds  are  often  formed  in  canned  goods  in 
the  steam  retort  by  oxidation,  and  the  analyses  recently  made  by 
certain  state  chemists  were  faulty  in  the  extreme  and  produced  the 
impression  that  these  chemicals  had  been  purposely  added  to  the 
samples  analyzed,  when  I  know  it  to  be  a  fact  that  they  were  not. 
They  should  have  known  from  the  very  nature  of  the  goods  they 
were  analyzing  that  oxidation  would  naturally  take  place  at  the 
temperatures  to  which  the  goods  had  been  submitted,  that  traces 
of  these  germicides  would  be  formed.  Far  be  it  from  me  to  in 
any  way  discourage  the  efforts  put  forth  by  conscientious  investi- 
gators to  improve  the  quality  of  food,  by  condemning  right  meth- 
ods; but  when  the  canning  industry  is  assailed  unjustly,  and  with 
the  motive  possibly  of  gaining  notoriety,  it  is  proper  to  protect  the 
manufacturers  and  furnish  them  with  information  to  refute  false 
analytical  reports.  I  personally  prepared  two  of  the  samples,  ab- 
solutely pure  in  every  respect,  which  were  submitted  to  the  state 
chemists  and  their  report  showed  that  formaldehyde  and  benzoates 
were  present,  which  was  false  in  the  sense  that  they  had  been  add- 
ed, and  that  report  gave  a  w^rong  impression  to  the  public.  They 
should  have  known  that  these  had  not  been  purposely  added,  but 
that  the  faint  traces  were  due  entirely  to  oxidation  produced  by 
steam  heat  250° F.,  and  that  the  product  would  naturally  yield 
traces  of  such  preservatives. 

To  return  to  our  subject,  we  have  found  that  sunlight  is 
germicidal  and  that  diffused  light  and  electric  light  are  slightly  in- 
jurious to  bacteria.  This  will  overthrow  the  idea  that  wrapping 
with  brown  paper  and  storing  in  dark  places  fruits  and  vegetables 
canned  in  tin  and  glass  would  prevent  fermentation.    Bacteria  grow 


BACTERIA.— DESCRIPTION  AND  CLASSIFICATION. 


03 


best  in  the  dark  and  the  only  vaUie  in  the  ancient  custom,  was  pro- 
tection from  dust  and  protection  of  color,  which  sunlight  injures 
to  some  extent. 

MOTIT^ITY. 

My  first  impression  when  observing  the  rapid,  almost  marvel- 
ous movement  of  certain  bacteria  was,  that  they  must  surely  be- 
long to  the  animalcules.  So  rapid  was  their  movement  that  the 
eye  could  not  possibly  follow  them.  Having  focused  the  edge  of  a 
hanging  drop  culture  of  the  typhoid  bacillus,  I  tried  over  and  over 
to  move  the  slide  and  keep  in  focus  with  the  fine  adjustment  of 
the  microscope,  the  swift  moving  germs,  but  they  quickly  passed 
out  of  the  field  or  dropped  so  deep  in  the  fluid  that  it  was  impossi- 
ble for  me  to  follow  them.  Other  active  varieties  also  are  apt  to 
create  the  impression  that  they  are  not  a  part  of  the  vegetable 
kingdom,  but  their  life  history  and  manner  of  vegetation  dispels 
the  doubt. 


x\— Monotricha 

a — Cholera  Bacilli. 

b — Sarcina  Pulmonum. 


Fig.  26 

B  —  IvOphotricha. 

a — Spirillum  Undula. 

b — Back  Syncyaneum. 


C — Peritricha. 
a — B.  Vulgatus. 
b — B.  Prodigiosus. 
c — Typhoid  Bacilli. 


Pasteur  regarded  the  "vibrion  butyrique"  as  an  animalcule  in 
his  early  researches,  but  the  higher  order  of  algae  have  motile 
spores  and  their  movements  are  extremely  rapid  too,  showing  that 
the  vegetable  kingdom  does  have  actively  motile  species,  and  mo- 
tility could  not  be  an  argument  in  opposition  to  their  place  in  this 
kingdom. 

There  are  two  kinds  of  motion  observed  in  bacteria,  one  a 
molecular  motion,  sometimes  called  ''Brownian  motion;"  the  other 
is  called  independent  motility.  The  former  is  purely  a  physical 
motion  and  may  be  noticed  in  many  particles  held  in  liquid  sus- 
pension. There  seems  to  be  an  oscillating  motion  peculiar  to  many 
micrococci  and  bacilli,  a  rotary  or  orbit  motion,  due  perhaps  to  the 
vibration  of  the  fluid.  The  molecules  of  the  fluid  may  be  round 
like  shot  and  roll  over  and  over  as  slight  chemical  changes  occur 
or  by  shock  or  by  the  influence  of  the  earth,  etc.  Certainly  no  one 
has  ever  seen  a  molecule  of  water,  but  it  seems  probable  that  the 
two  atoms  of  hydrogen  and  the  one  atom  of  oxygen  might  combine 
into  a  spherical  molecule,  and  if  such  be  the  case  there  would  prob- 


54  CANNING    AND    PRESERVING    OP    FOOD    PRODUCTS. 

ably  be  great  oscillation  going  on  continually,  thus  accounting  for 
the  peculiar  movement  described  as  ''Brownian  movement."  Cohen 
made  some  experiments  which  seem  to  lend  color  to  the  theory 
given  above.  Gelatin  was  gradually  added  so  that  all  the  particles 
held  in  suspension  became  quiet  and  he  noticed  that  all  bacteria 
which  had  no  independent  motion,  also  became  quiet,  while  the 
bacteria  which  had  an  independent  motion  moved  quite  freely. 

The  subject  has  not  been  fully  investigated  and  the  theory 
of  molecular  oscillation  will  probably  stand. 

Bacteria  which  have  independent  motion  are  endowed  with 
organs  of  locomotion  which  are  most  interesting  to  study.  These 
organs  are  called  by  different  authors  f  la  gel  la,  celia,  or  whips,  which 
grow  out  either  from  the  ends  or  sides  of  the  bacilli  or  both.  The 
number  and  kind  of  flagella  often  determine  the  species  to  which 
a  certain  bacillus  belongs.  These  organs  of  locomotion  were  first 
discovered  by  Ehrenberg  in  1836,  and  more  carefully  studied  by 
Cohen.  It  was  supposed  for  a  long  time  that  only  bacilli  were 
thus  endowed,  but  in  1887  and  1890  Loeffler  and  several  others 
claimed  to  have  discovered  certain  cocci  which  were  motile,  but 
this  is  doubtful. 

These  flagella  are  not  visible  when  the  bacteria  are  stained 
with  ordinary  dyes;  the  most  powerful  objectives  do  not  clearly 
show^  their  presence  unless  special  staining  is  done  to  bring  them 
into  view.  Some  bacteria  have  only  one  polar  flagellum.  Others 
have  two  or  may  have  a  bunch  at  the  end;  still  others  have  them 
evenly  distributed  over  the  entire  surface  of  the  cell,  sometimes  as 
many  as  a  hundred.  The  number  and  size  of  the  flagella  depend 
upon  the  age  of  the  cells.  Usually  they  are  best  seen  and  studied 
in  cultures  24  to  36  hours  old. 

Flagella  are  very  thin,  hair-like  appendages,  so  fine  that  the 
dyes  must  be  piled  upon  them  to  bring  them  into  vision ;  they  vary 
in  length  from  two  to  twenty  times  the  length  of  the  bacillus  and 
seem  to  derive  active  power  from  the  cell  itself  so  that  they  im- 
part peculiar  motion  to  the  rods ;  some  having  a  wabbling  motion, 
others  a  creeping  motion,  others  a  snakedike  motion  and  still  others 
turn  somersaults  and  whirl  with  a  rapidity  truly  remarkable;  and 
the  spirochetae  have  a  boring  or  corkscrew  movement.  Bacilli  are 
classified  with  reference  to  the  number  of  flagella  (see  Fig.  26) 
into  four  groups — monotricha,  having  one  flagellum  at  the  end ; 
amphitricha,  having  a  flagellum  at  both  ends;  lophotricha,  having 
a  bunch  of  two  or  more  at  the  end ;  and  peritricha,  having  the  whole 
surface  arrayed  with  the  hair-like  whips. 

These  propelling  organs  are  so  delicate  that  they  are  easily  in- 
jured and  fall  off  or  become  looped  when  disturbed  by  external 
influences.  When  they  are  thus  injured  they  disappear  very  soon 
and  are  apparently  dissolved  in  the  fluid  surrounding  them.     They 


BACTERIA.— DESCRIPTION  AND  CLASSIFICATION. 


55 


often  fall  off  just  at  the  time  of  spore  formation.  This  is  true  of 
nearly  all  species  excepting  some  anaerobic  bacteria.  Old  cultures 
therefore  are  not  suitable  for  the  demonstration  of  flagella.  I  want 
to  emphasize  this  point  because  the  beginner  will  have  considerable 
trouble,  even  under  the  most  favorable  circumstances,  to  stain  the 
delicate  celia  property;  a  young  culture  is  always  to  be  preferred. 

The  influence  of  chemicals,  antiseptics,  salicylic  acid,  benzoates, 
etc.,  is  such  as  to  cause  loss  of  motion  or  death  to  bacteria,  but 
loss  of  motion  does  not  always  mean  that  the  bacteria  are  dead. 
Often  they  may  be  transplanted  into  favorable  nutrient  media  and 
become  as  actively  motile  as  before.  The  enzymes  and  toxins  which 
are  the  products  elaborated  by  the  bacteria  themselves  when  grow- 
ing in  a  favorable  substratum  (nutrient  substance),  often  cause  loss 
of  motion  and  the  agglutination  (gathering  in  bunches),  tests  are 
made  possible  by  this  characteristic.  This  phenomenon  is  most 
valuable  to  the  bacteriologist  in  determining  cases  of  typhoid  fever. 
Where  the  patient  has  typhoid  fever  the  poison  very  early  is  dis- 
tributed through  the  blood  and  this  poisoned  blood  Avill  cause  the 
agglutination  of  the  typhoid  bacilli  when  they  are  introduced  into 
a  drop  of  the  serum,  diluted  with  bouillon. 

Sometimes  the  microscopist  meets  with  peculiar  bodies  in  a 
field   or  view  where  a   pure   culture   of   motile  bacteria   is   being 


Plate  8.     Giant  Whips  of  Malignant  Oedema 

Photomicrograph  showing  rods  and  giant  whips.  These  large  twisted  bodies  are  visible  in  the  water  of 
condensation  without  staining.  Nearly  all  motile  anaerobic  bacteria  produce  these.  Just  what  they  are  has  not 
been  determined,  but  their  presence  is  interesting.     Magnified  2,000  diameters. 


56  CANNING    AND    PRESERVING    OF    POOD    PRODUCTS. 

Studied.  Loeffler  in  1890  observed  large  spindle-shaped  bodies  re- 
sembling twisted  hair.  Later  in  1893  Novy  observed  these  same 
bodies,  which  he  calls  ''giant  zvhips,"  while  studying  various  an- 
aerobic bacteria.  Fischer,  Sakharoff  and  Sames  also  describe  these 
large  spindle-shaped  bodies. 

The  spirals  are  very  large,  varying  from  20  to  lOOiu  in  length, 
and  may  be  observed  without  resorting  to  stains,  in  the  water  of 
condensation  of  freshly  inclined  agar  in  tubes  inoculated  with  cul- 
tures of  motile  bacteria.  They  are  motionless  and  have  a  wavy 
appearance,  or  resemble  a  spindle  wrapped  in  twine. 


Plate  9.     Giant  \\lii[)s  ot  Barillus  Butyricus  Frumenti 

Photomicrograph  of  Bacillus  Butyricus  Frutnenti,  showing  ordinary  flagella  and  also  a  bunch  of  giant 
whips  greasly  resembling  a  bunch  of  hair.  This  is  an  obligative  anaerobic  bacillus  found  in  corn  and  was  ab- 
tained  from  a  swelled  can  of  corn.  The  pressure  of  gas  created  by  this  organism  is  enormous,  sufficient  to  burst 
the  cans.  Stained  by  our  special  method  from  a  young  growth  on  2  per  cent,  glucose  agar.  Photographed 
through  a  2  mm.  oil  immersion  objective  using  acetylene  radiant.     Magnified  1,200  diameters. 

The  staining  and  demonstration  of  flagella  will  be  fully  ex- 
plained later.  It  is  accomplished  only  with  great  care  and  fine 
mountings  are  obtained  only  by  practice  and  patience. 

CHROMOGENIC    BACTERIA. 

Chromogenic  bacteria  are  the  species  which  produce  pigments 
or  colors  of  various  shades  and  play  an  important  part  in  the 
deterioration  of  food  products.  There  are  two  classes — Chromo- 
parous  and  Cromophorous. 

CHROMOPAROUS,  or  color  producing  bacteria,  are  them- 
selves colorless,  but  they  produce  pigments  of  various  shades  which 
give  distinct  colors  to  the  food  stuffs  on  which  they  are  growing. 


BACTERIA.— DESCRIPTION  AND  CLASSIFICATION.  57 

THE  CHROMOPHOROUS  group  produce  colors  within  the 
cells,  and  may  or  may  not  give  off  the  color  to  the  media  upon 
which  they  are  growing.  The  colors  produced  by  the  chromo- 
genic  bacteria  can  be  distinguished  by  their  behavior  towards  sol- 
vents. The  same  bacteria  always  produce  the  same  color  when 
grown  in  the  same  temperature  and  in  the  same  media.  Identical 
colors  may  be  produced  by  more  than  one  variety,  but  the  varieties 
may  be  differentiated  by  the  chemical  reactions  of  their  pigments. 

The  red  colors  are  frequently  seen  like  drops  of  blood  on  many 
cooked  vegetables,  such  as  potatoes,  starch,  flour,  Qgg  albumen,  car- 
rots, meats,  milk,  onions  and  others  which  enter  into  the  formulas 
of  soups,  sauces,  etc.  Cane  sugar  syrup  is  often  affected  by  these 
colors.  The  oldest  known  bacterium  producing  a  red  color  is  Bac- 
terium prodigiosum.  Cultures  of  this  organism  were  used  by  magi- 
cians years  ago  to  imitate  blood  spots  on  bread,  whence  its  name 
of  "Bleeding  bread"  originated.  There  are  several  forms  closely 
allied  to  this,  which  produce  various  shades  of  red  from  a  pink  to 
a  deep  brown  red. 

Milk  is  particularly  subject  to  changes  in  color  by  these  organ- 
isms ;  also  cheese ;  but  such  colors  in  these  products  may  be  pro- 
duced by  other  causes  such  as  blood,  or  madder  (Rubia  tinctorum 
in  the  fodder  fed  to  the  cow.  Sometimes  cheese  assumes  a  red  color 
from  a  purely  chemical  change  caused  by  the  oxidation  of  iron 
compounds  which  develop  during  the  ripening  of  the  curd.  These 
chemical  changes  are  quite  easily  distinguished  from  the  red  colors 
produced  by  bacteria.  More  frequently  cheese  owes  its  red  dis- 
coloration to  mold  fungi  belonging-  to  the  group  of  Eumycetes. 

Dried  codfish  is  very  susceptible  to  red  colors  so  that  it  resem- 
bles salmon.  Three  different  varieties  which  cause  the  trouble  have 
been  studied  by  Le  Dantec,  who  states  that  the  loss  is  estimated 
to  be  about  ten  million  francs  annually,  since  the  people  believe  that 
codfish  affected  with  this  color  is  poisonous. 

YELLOW  COLORS  are  produced  by  a  number  of  bacteria, 
but  very  few  foods  are  affected  by  them  excepting  milk.  Milk 
sometimes  develops  a  pale  orange  yellow  and  the  bacteria  causing 
it  were  first  studied  by  C.  J.  Fuchs  in  1841  and  by  J.  Schroeter  in 
1870,  the  latter  isolating  two  microbes  named  Vibrio  Xanthogenus 
and  Bacterium  synxanthum  as  the  cause,  but  he  claimed  that  they 
were  found  in  milk  only  after  boiling.  The  yellow  pigment  pro- 
duced by  these  germs  is  soluble  in  water,  but  not  in  alcohol  nor 
ether. 

BLUE  COLORS  are  produced  by  several  varieties  of  mi- 
crobes and  the  principal  foodstuffs  affected  are  milk  and  cheese. 
Milk  and  cheese  enter  into  the  formulas  for  manufacturing  so  many 
different  varieties  of  food  products  that  the  manufacturer  of  soups 


58  CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 


Bacillus  Prodigiosus 

MONAS    PRODIGIOSA,    OF    EHRENBERG.      MICROCOCCUS    PRODIGIOSUS. 

^  Origin. — It  is  found  on  starchy  substances,  such  as  rice,  potatoes, 
moist  bread;  also  on  meat,  albumen,  milk,  etc.  Causes  at  times  local 
epidemics,  infecting  foods,  as  bread,  sausages,  meat,  etc.,  to  which  it  gives 
a  pinkish  or  red  color.  Bread  so  affected  has  been  called  "Bleeding 
bread." 

Form. — A  short  rod,  slightly  longer  than  it  is  wide;  it  sometimes 
forms  threads,  especially  in  slightly  acid  media  or  in  old  cultures;  usually 
single  or  in  pairs. 

Motility. — It  shows  no  motion  ordinarily  except  a  marked  Brownian 
movement.  The  slimy  character  of  the  growth  decreases  in  acid  or  very 
dilute  media,  and  a  slight  motion  may  be  observed.  It  has  numerous  long 
wavy  flagella. 

Sporulation. — This  has  not  been  observed.  It  shows  marked  resist- 
ance to  dessication. 

Anilin  Dyes. — Stain  readily. 

Grozvth. — The  growth  is  very  rapid. 

Gelatin  Plates. — Deep  colonies  are  round  or  oval,  light  brown  in  color 
and  with  sharp  border.  The  surface  colonies  are  irregular,  with  rough 
border,  granular,  have  reddish  center,  and  are  surrounded  by  clear,  lique- 
fied  gelatin. 

Stab  Culture. — The  liquefaction  is  rapid  and  funnel-shaped,  and  ex- 
tends along  the  whole  line  of  inoculation.  A  red  scum  is  formed  on  the 
surface  of  the  liquid,  which  on  settling  colors  the  entire  contents  a  bright 
red. 

Streak  Culture. — On  agar,  it  forms  a  spreading  growth  which  is  moist 
and  abundant  and  of  an  intense  red  color,  which  is  non-diffusible.  On 
potato,  it  grows  very  rapidly,  producing  slime  and  a  pigment,  which,  when 
old,  has  a  metallic,  fuchsine-like  luster.  Odor  of  trimethylamin.  On 
blood-serum,  growth  is  same  as  on  agar,  with  liquefaction. 

Milk. — Growth  takes  place  and  the  fat  globules  hold  the  pigment  in 
solution.     Coagulation    results. 

Oxygen  Requirement. — It  is  a  facultative  anaerobe. 

Temperature. — It  grows  best  at  ordinary  room  temperature.  It  ceases 
to  form  pigment  in  the  incubator  and  may  lose  this  property  temporarily, 
i.  e.,  become  attenuated. 

Behavior  to  Gelatin. — Rapidly  liquefies  as  the  result  of  formation  of 
a  soluble  peptonizing  ferment.  In  acid  media  this  liquefying  property 
may  be  diminished  or  temporarily  lost. 

Aerogenesis. — It  has  a  strong  odor  of  trimethylamin  on  potatoes,  and 
ferments   sugar  solutions. 

Pigment  Production. — A  bright  red  pigment  is  formed  on  various 
media,  and  this  is  soluble  in  ether,  alcohol,  chloroform,  etc.  This  pig- 
ment is  formed  only  in  the  presence  of  air  and  at  ordinary  temperatures — 
not  at  37°. 

Pathogenesis. — It  is  non-pathogenic.  In  large  amounts  its  soluble  pro- 
ducts may  have  a  toxic  action.  The  cellular  proteins  may  induce  suppura- 
tion. Animals  which  are  not  susceptible  to  malignant  oedema  may  be  ren- 
dered susceptible  by  an  injection  of  this  bacillus.  An  injection  of  this 
bacillus  saves  rabbits  inoculated  with  anthrax. 


BACTERIA.— DESCRIPTION  AND   CLASSIFICATION.  59 

and  sauces  will  no  doubt  be  interested  in  these  phenomena,  which 
he  has  perhaps  frequently  met  with. 

The  principal  microbe  which  produces  blue  colors  in  milk  is 
named  Bacillus  Cyano genus;  but  blue  discoloration  may  be  ob- 
served also  in  freshly  drawn  milk  where  the  cow  has  fed  on  the 
flowering  rush  (Butomus  umbellatus)  which  contains  a  blue  color- 
ing matter  frequently  carried  into  the  milk  from  the  stomach  of 


Plate  10.     Bacillus  Prodigiosus,   Flagellated 
Magnified  1,200  diameters. 

the  cow  through  the  arteries  and  mammillary  glands.  The  dis- 
tinction can  easily  be  made  between  these  two  causes  by  adding  a 
small  quantity  of  each  kind  of  milk  to  normal  milk.  The  one  con- 
taining the  Bacillus  Cyanogenus  will  soon  produce  the  blue  color 
in  the  normal  milk,  while  there  will  probably  be  no  change  notice- 
able in  the  other. 

Bacillus  is  a  motile  organism  requiring  oxygen  for  luxuriant 
growth;  the  rods  measuring  from  .3/x  to  .^i^  broad  to  1.4/A  long. 
When  a  dairs^  becomes  afifected  with  this  organism  it  is  most  diffi- 
cult to  get  rid  of  it,  often  requiring  complete  changes  in  all  utensils 
and  thorough  disinfection.  This  microbe  grows  well  on  vegetables 
which  have  been  cooked,  such  as  rice  and  potatoes,  which  are  used 
in  various  formulas  by  the  canner. 


60  CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 


Bacillus  Cyanogenus,  Fuelis     (1841) 

BACILLUS    OF    BLUE    MILK. 

Origin. — Found  in  blue  milk. 

Form. — Small,  rather  narrow  rods,  having  slightly  rounded  ends,  two 
to  three  times  as  long  as  wide.  Frequently  found  in  paris ;  rarely  in 
threads. 

Motility. — It  is  very  actively  motile ;  has  bunch  of  whips  at  one  end. 

Sporulation. — The  small  terminal  bodies  resembling  spores  are  most 
probably  involution   forms.     True   spores   may  form  on   althea  or  quince 

Anilin  Dyes. — Stain  readily. 

Growth. — Rapid. 

Gelatin  Plates. — The  deep  colonies  are  round,  having  sharp,  smooth 
border ;  contents  are  yellowish  and  granular.  The  surface  colonies  are 
round,  moist,  elevated,  convex  masses,  finely  granular  and  dark  in  color; 
at  times  they  may  be  thin  and  spreading,  having  an  irregular  border. 

Stah  Culture. — In  the  lower  part  of  the  puncture  there  is  little  or  no 
growth.  There  is  a  thick,  moist,  dark-gray,  spreading  growth  on  the  sur- 
face. Gelatin  is  colored  a  dark  steel-blue,  the  shade  varying  with  the  re- 
action of  the  medium,  being  quite  blue  in  neutral  or  acid  media  and  dark, 
or  even  black,  in  very  alkaline  media.     It  becomes  dark  colored  when  old. 

Streak  Culture. — On  agar,  a  dirty  gray,  ihick,  moist  covering  is 
formed,  the  medium  becoming  dark  colored.  On  potato,  a  similar  growth 
is  formed  which  r.?pidly  spreads  and  becomes  colored.  On  blood-serum, 
it  forms  no  color. 

Milk. — It  produces  no  acid  or  coagulation  in  sterilized  milk,  but  the 
milk  is  colored  a  slate-gray,  which  turns  blue  with  acids.  In  unsterilized 
milk,  in  the  presence  of  lactic  acid  bacteria,  the  color  is  sky-blue.  This 
color  develops  from  casein  and  not  from  lactose.  In  bouillon  or  milk  con- 
taining 2%  of  glucose,  lactic  acid  and  a  fine  blue  color  are  formed.  Lac- 
tose is  not  converted  into  an  acid. 

Oxygen  Requirements. — Aerobic. 

Temperature. — Grows  best  at  ordinary  temperature,  but  will  grow  in 
incubator.  The  pigment  is  most  marked  when  it  is  grown  at  low  tem- 
peratures, 15°  to  i8°  C. 

Behavior  to  Gelatin. — Does  not  liquefy. 

Pathogenesis. — No  effect  on   animals. 


BACTERIA.— DESCRIPTION  AND   CLASSIFICATION.  61 

GREBN  COLORING  matter  is  excreted  by  quite  a  number 
of  bacteria,  some  of  which  in  the  presence  of  phosphates  give  the 
green  color  while  in  other  media  their  natural  blue  color  is  pre- 
dominant; among  these  may  be  mentioned  Bacillus  pyocyaneus, 
which  causes  the  green  color  observed  in  meat  which  has  been  ex- 
posed to  the  air.  This  is  the  same  organism  which  gives  rise 
to  the  green  pus  often  seen  on  wound  bandages.  Bacillus  butyri 
fluorsecens,  a  fission  fungus,  was  discovered  by  Dr.  T.  Lafar  in 
1 89 1  as  the  cause  of  green  discoloration  sometimes  seen  in  but- 
ter. Among  the  more  common  varieties  which  produce  green  pig- 
ment, the  following  may  be  mentioned : 


# 

Plate  11.     Bacillus  Cyanogenus,  Flagellated 
Magnified  1,000  diameters. 

Bacillus  fluorescenes  putidus,  Bacillus  fl.  tenuis,  Bacillus  albus. 
Bacillus  viridans  and  Bacterium  syncyaneum;  while  various  molds 
present  a  green  appearance  but  do  not  impart  their  coloring  to  the 
substratum  upon  which  they  grow.  The  mold  Penicillium  glaucum 
gives  the  green  color  to  Roquefort,  Gorgonzola,  Stilton  and  Brie 
cheese.  There  have  been  discovered  some  twenty-seven  species  of 
Penicillium.  The  green  observed  in  several  kinds  of  cheese  it  not 
due  to  bacteria  nor  fungi,  but  to  copper  which  was  absorbed  from 


62  CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 


Penicillium  Glaucum 

Origin. — It  is  widely  distributed  in  air,  water  and  soil.  It  is  said 
that  sixty  per  cent  of  the  mold  contaminations  in  the  laboratory  are  due 
to  it. 

Color. — Whitish  at  first,  changing  to  a  bluish-green  later. 

Mycelium. — Is  composed  of  straight  or  slightly  wavy  mycelial  threads 
horizontally  arranged;  from  these  the  fruit  hyphae  rise  vertically. 

Fruit-organs. — The  ends  of  the  septate  fruit  hyphae  are  forked;  they 
are  covered  with  sterigmae,  sometimes  called  besidia.  Each  of  these 
sterigmae  bears  a  row  of  eight  spores  or  conidia,  giving  to  the  whole  the 
appearance  of  a  brush.     The  spores  are  about  3.5  ju,  in  width. 

Growth. — Rapid. 

Gelatin  Plates. — Whitish  floccules  are  formed  by  the  colonies;  these 
gradually  increase  in  size;  at  the  same  time  the  center  becomes  a  green 
color.  The  gelatin  is  liquefied  early.  The  above  characteristics  may  be 
seen  by  means  of  a  low  objective. 

Bread  Flasks. — A  low,  finely  flocculent  covering  is  formed,  white  at 
first,  but  changing  to  green  later. 

Temperature. — Optimum,  from  22°  to  26''  C  will  not  grow  at  body 
temperature. 

Behavior  to   Gelatin. — Liquefies  slowly. 

Pathogenesis. — No  effect  on  animals.  It  often  develops  on  grapes  and 
causes  a  marked  alteration  in  wine.  Gives  rise  to  diastatic  and  inverting 
ferments.     It  is  said  to  be  used  in  the  preparation  of  Roquefort  cheese. 


BACTERIA.— DESCRIPTION  AND  CLASSIFICATION. 


ea 


Plate  12.     Penicillium    Glaucum 

Magnified  600  diameters. 


Plate  13.     Penicillium    Glaucum 

Photomicrograph  of  a  bluish  green  mold  belonging  to  a  species  of  Penicillium,  which  was  found  on  the- 
surface  of  jelly.  The  photograph  was  made  of  the  living  plant  and  shows  the  mycelium,  hyphae  and  spores. 
The  spores  are  flat  on  both  sides  and  are  capable  of  setting  up  fermentation  when  submerged  in  fruit  juices.  It: 
will  form  alcohol,  some  acid  and  phenol-like  bodies.     Magnified  500  diameters. 


BACTERIA.— DESCRIPTION  AND  CLASSIFICATION.  65 

copper  utensils,  in  which  tlie  milk  had  been  kept.  The  lactic  acid 
formed,  attacked  the  copper,  which  turned  green  in  the  yellow 
cheese. 

Canners  of  meats  should  guard  against  the  use  of  meat  which 
shows  any  green  discoloration.  The  presence  of  the  green  pigment 
indicates  that  the  meat  has  been  exposed  to  warm  temperature  and 
may  have  more  deadly  parasites  flourishing  on  the  surface  and  in 
the  tissues  than  the  color-bearing  germs.  There  are  various  bac- 
teria and  fungi  which  produce  other  colors  such  as  black  smut  and 
white  spots.     Packers  of  corn  often  experience  trouble  with  black 


Plate  14.     Yellow  Mold 

Photomicrograph  of  a  beautiful  yellow  colored  mold  isolated  from  the  surface  of  California  tumbler  jelly. 
This  is  a  very  rare  species  and  grows  in  almost  similar  manner  as  Penicillium,  having  the  branched  hyphae  and 
the  long  rows  of  conidia  or  spores  at  the  end.  This  specimen  was  photographed  from  the  edge  of  an  agar 
growth  in  the  living  state,  sunlight  being  used  in  two  ways,  both  direct  and  by  transmission,  giving  the  plate  a 
beautiful  relief-like  effect.     Magnified  500  diameters. 

spots  throughout  their  cans,  sometimes  due  to  these,  which  will  be 
fully  described  under  the  head  of  Corn  Packing.  The  packers  of 
canned  lobsters  have  had  considerable  trouble  at  times  with  black 
discoloration,  as  also  do  packers  of  various  sea  foods,  all  of  which 
will  be  described  in  their  proper  places. 

There  are  varieties  of  bacteria  which  produce  violet  and  pur- 
ple colors  which  are  useful  in  the  manufacture  of  indigo  and  other 
shades,  but  have  no  importance  in  the  manufacture  of  food  prod- 
ucts. 


66 


CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 


BACTERIA  PRODUCING  SLIME  AND  ROPINESS  IN  FOOD  PRODUCTS. 

Viscous  fermentation  is  a  most  important  study  for  the  can- 
ners  of  molasses,  syrups  and  vegetables,  such  as  peas,  string  beans, 
asparagus,  etc.  Grape  sugar  is  often  split  up  by  Invertin,  pro- 
duced by  several  varieties  of  bacteria  which  form  mucinous  cap- 
sules and  grow  in  zoogloea  or  masses  all  united.  There  are  cocci 
which  grow  on  some  foodstuffs  without  forming  the  gelatinous 
capsules.  The  capsules  are  formed  as  a  sticky  envelope  around 
the  cocci,  and  sugar,  lactose,  maltose  and  dextrin  seem  to  favor 
their  development.  The  capsules  are  stained  by  special  dyes  and 
are  not  revealed  by  ordinary  staining. 


Fig.  27.     Leuconostoc   Mesenteroides 

a.  b. — Chains  of  non-capsuled  variety.      c.  e. — Cells  with  gelatinous  capsules  in 
various  stages  of  development.     (X  1,200.     After  Liesenburg  and  Zopf.) 

The  principal  cause  of  this  viscous  fermentation  in  cane  sugar 
are  the  Leuconostoc  mesenteroides,  which  were  studied  by  Van 
Teighem  in  1878,  wdio  published  his  researches,  but  he  probably 
had  several  varieties  mixed,  as  his  drawings  show  chains  of  cocci 
and  diplococci.  In  1891,  however,  C.  Liesenberg  and  W.  Zopf  ob- 
tained pure  cultures  of  the  organism  and  found  it  to  be  a  coccus 
o.Sfi  to  i.o/x  in  diameter. 

This  germ  does  not  develop  the  mucinous  matter  when  grow- 
ing on  nutrient  substances  free  from  sugar,  but  when  grown  on 


BACTERIA.— DESCRIPTION  AND  CLASSIFICATION.  67 

vegetables  like  peas,  beans,  beets  and  carrots,  which  contain  saccha- 
rose and  dextrose,  zooglea  forms  appear,  somewhat  dry  at  first, 
afterwards  becoming  softer  and  sticky.  Frequently  whole  vats  of 
molasses  will  be  contaminated  by  this  microbe  and  when  it  acts  on 
cane  sugar  syrup,  it  produces  the  invertin  which  retards  crystalli- 
zation. The  capsule  which  surround  it  protects  it  and  enables  it 
to  withstand  high  temperatures. 

Another  cause  of  viscous  fermentation  is  the  Bacillus  Vis- 
cosus  Sacchari,  which  differs  from  the  last  organism  described  in 
that  it  converts  the  media  on  which  it  develops  into  a  viscid  mass 
and  does  not  form  the  envelope  around  the  cell. 

There  are  several  other  varieties  which  cause  viscous  fermen- 
tation, viz. :  Bacillus  megatherium.  Bacillus  fluorescens  liquefaciens, 
Bacillus  vulgatus  and  others  which  produce  changes  in  saccharine 
products,  giving  rise  to  mucus,  amyl  alcohol  and  invertin.  Milk 
frequently  becomes  ropy  or  slimy  so  that  it  can  be  lifted  up  in  long 
stringy  threads,  sometimes  a  yard  in  length.  Alcohol  and  acetic 
acid  are  often  generated  in  this  kind  of  milk  by  two  organisms 
isolated  by  E.  Duclax,  called  by  the  generic  name  Actinobacter 
or  lustrous  bacteria. 

Bacillus  mesentencus  vulgatus  (Flugge)  and  Bacillus  pitui- 
tosi  fLoeffler)  are  most  frequently  the  cause  of  ropiness,  but  re- 
cently I  have  observed  a  short,  plump  capsuled  bacillus  in  cream 
which  had  become  ropy.  This  bacillus  wdien  grown  on  nutrient 
agar  develops  the  capsules  and  takes  the  stains  quite  readily.  It 
resembles  the  Bacillus  lactis  viscosus,  discovered  by  L.  Adametz 
in  1890.  All  these  organisms  develop  at  times  in  milk  which  is 
allowed  to  stand  in  a  warm  temperature ;  this  is  easily  avoided,  but 
there  is  another  organism  which  develops  ropiness  at  a  lower  tem- 
perature. It  is  a  large  micrococcus  about  2a  in  diameter,  easily 
killed  by  boiling  temperature. 

The  peculiar  flavor  of  Edam  cheese  is  due  to  a  fission  fungus 
called  Streptococcus  hollandicus,  cultivated  in  pure  cultures  by  the 
Dutch  dairymen  and  cheesemakers.  Milk,  when  sown  with  this 
fungus,  soon  becomes  ropy  and  the  ropy  whey  is  made  into  the 
famous  cheese. 

In  Finland,  Sweden  and  Norway  the  milk  pails  are  rubbed 
on  the  inside  with  the  leaves  of  the  butterwort  (Pinguicula  vul- 
garis) and  the  cow^s  are  fed  with  the  plant.  The  leaves  of  this 
plant  are  infested  Avith  the  micro  organism  used  by  the  Dutch 
cheesemakers,  consequently  the  milk  is  soon  ropy,  and  this  thick 
milk,  is  a  commercial  article  among  the  Scandinavians, 

Soapy  or  frothy  milk  with  a  slimy  sediment  is  due  to  a  mi- 
crobe called  by  Weigmann,  Bacillus  lactis  saponacei,  usually  the 
result  of  unclean  bedding  for  cows.  Many  of  the  impurites  in  milk 
are  due  to  the  uncleanly  methods  of  dairymen,  and  it  is  hoped 


68  OANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 


Bacillus  Mesentericus  Vulgatus,  Flugge 

POTATO  BACILLUS. 

Origin. — They  are  widely  distributed  in  the  soil,  on  the  surface  of 
potatoes,  in  faeces,  putrid  fluids,  milk,  water,  etc. 

Form. — Small,  thick  rods,  having  rounded  ends.  Usually  found  in 
pairs ;  may  form  threads. 

Motility. — It  is  actively  motile,  having  numerous  flagella. 

Sporulaiion. — Large,  medium,  roundish  spores  are  readily  formed. 
Globing  describes  one  variety  which  showed  enormous  powers  of  resist- 
ance, withstanding  the  action  of  steam  heat  for  five  to  six  hours. 

Anilin  Dyes. — React  easily,  as   does  also  Gram's  method. 

Grozvth. — Very  rapid,  resembling  in  many  respects  that  of  the  hay 
bacillus. 

Gelatin  Plates. — The  colonies  are  yellowish-white,  slightly  granular, 
with  irregular  borders,  liquefying  rapidly  and  extensively. 

Stab  Culture. — Growth  along  er.tire  line  of  inoculation,  liquefaction 
being  more  energetic  in-  the  upper  part.  The  liquefied  gelatin  remains 
turbid  for  some  time.  A  thin,  grayish,  folded  scum  is  formed  on  the 
top. 

Streak  Culture. — On  agar  a  dull  white  or  grayish  growth  is  formed. 
The  most  characteristic  growth  develops  on  potato. The  surface  is  rapidly 
covered  with  a  thick,  white,  strongly  folded,  coherent  growth,  which 
later  becomes  a  dirty  brown  or  red  color. 

Mild. — Casein  is  coagulated  and  peptonized,  and  starch  is  inverted. 

Oxygen  Requirements. — Aerobic. 

Temperature. — Growth   at   ordinary   or  at  higher   temperatures. 

Behavior  to  Gelatin. — Liquefies  rapidly. 

Pathogenesis. — No   effect   has   been  observed. 

There  are  several  varieties  of  potato  bacilli,  some  forming  a  red  and 
others  a  brown  growth  on  potato.  The  spores  of  the  potato  and  hay  ba- 
cilli are  extremely  resistant — it  may  require  an  exposure  of  ten  hours  or 
more  to  steam  to  insure  sterilization  when  the  material  is  in  a  small  mass, 
not  in  a  fine  state  of  suspension. 


BACTERIA.— DESCRIPTION  AND  CLASSIFICATION.  69 

that  more  stringent  laws  may  be  passed  to  keep  this  universal 
food  product  purer  and  more  wholesome.  Milk  is  so  extensively 
used  in  the  manufacture  of  delicate  soups,  sauces  and  table  delica- 
cies that  its  special  study  is  desirable. 


(  ^ 


Plate  15.     Bacillus  Mesentericus  Vulgatus,  Flagellated 

Magnified  1,200  diameters. 

In  the  manufacture  of  Worcestershire  sauce,  wine  is  used  fre- 
quently, and  is  sometimes  found  to  be  ropy  and  slimy,  the  flavor 
greatly  injured.  The  study  of  this  subject  is  one  more  for  the 
wine  maker  than  the  manufacturer  of  food  products,  yet  it  is  well 
to  know  that  such  wine  is  not  fit  for  use  and  the  trouble  is  dtie 
to  fission  fungi  studied  by  Pasteur,  and  are  Bacillus  viscosus  vini 
and  other  similar  species. 

The  same  scientist  investigated  the  cause  of  beer  and  wort  be- 
coming ropy  and  found  a  fission  fungus  which  he  named  Micrococ- 
cus viscosus.  This  organism  does  not  give  rise  to  violent  fermen- 
tation, but  seems  to  perform  its  functions  in  the  development  of  a 


70 


OANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 


gelatinous  viscid  envelope  which  spreads  through  the  whole  liquid. 
H.  Van  Lear  obtained  pure  cultures  of  two  varieties,  naming  them 
Bacillus  Viscosus  I  and  II,  differing  in  the  quantity  of  carbon 
dioxid  liberated  and  the  amount  of  viscous  matter;  the  first  pro- 
duces yellow  patches  and  the  second  a  brown  formation. 

These  two  organisms,  contrary  to  the  general  character  of 
viscous  ferments,  do  not  require  sugar  in  very  large  quantities  to 
produce  the  gelatinous  envelope,  in  fact  sugar  is  injurious  to  them. 
In  the  manufacture  of  malt  and  cider  vinegar  these  organisms  make 
their  appearance,  frequently  causing  a  great  deal  of  trouble.  The 
alcohol  is  favorable  to  their  development  but  the  acidity  is  germi- 
cidal.    About  2  per  cent,  acid  stops  development. 


F 


-^1 


Plate  16.     Bacillus  Vulgatus  Viscosus,  Flagellated 

Photomicrograph  of  a  slime-forming,  actively  motile  bacillus.  This  is  a  spore-bearing  organism  similar  in 
some  respects  to  Bacillus  Vulgatus  in  its  formation  of  slime.  Incompletely  sterilized  molasses  is  fermented  and 
rendered  very  viscous  by  the  decomposition  of  sugar.  The  flagella  are  stained  by  precipitating  the  slime  with 
chloroform  and  staining  as  usual,  although  many  difficulties  beset  the  microscopist.     Magnified  1,000  diameteas. 


Viscous  fermentation  is  not  confined  to  the  family  of  bacteria 
(Schizomycetes)  alone,  but  may  be  caused  by  some  of  the  Eumy- 
cetes  or  yeast  and  mold  fungi  as  well. 

The  canner  and  preserver  has  difficulties  of  this  nature,  par- 
ticularly canners  of  molasses,  syrups,  peas,  beans,  corn,  asparagus, 
etc.  Owing  to  the  heat  resisting  power  of  many  species  which  are 
protected  by  their  gelatinous  capsules,  sterilization  is  sometimes 
difficult.     To  be  sure  the  temperature  may  be  increased  and  the 


BACTERIA.— DESCRIPTION  AND  CLASSIFICATION.  71 

time  lengthened,  but  the  quality  is  thereby  injured.  It  would  be 
no  trouble  to  increase  the  process  of  peas  to  one  hour  at  25o°F., 
which  would  perfectly  sterilize  them,  but  the  result  would  be  more 
of  a  soup  than  canned  peas — they  would  all  cook  to  pieces.  The 
remedy  lies  in  another  direction ;  the  raw  product  must  be  properly 
cared  for,  and  not  allowed  to  stand  exposed  to  these  scavengers. 
There  has  been  considerable  carelessness  in  this  matter  in  the  past. 
Raw  material  often  stood  exposed  until  the  slimy  formation  could 
be  detected  by  the  hand.  I  remember  when  the  new  pea  vining  ma- 
chinery first  came  into  use,  the  hulled  peas  were  hauled  several 
miles  on  wagons  in  baskets  eight  inches  deep.  They  were  unloaded 
and  piled  up  for  several  hours  before  they  were  canned,  and  the 
baskets  were  very  slimy  and  the  peas  stuck  together  so  that  the 
grading  machines  were  scarcely  able  to  properly  sort  them  into 
various  sizes.  The  cans  opened  after  the  season  were  ropy  and 
the  peas  were  flat  and  had  lost  their  delicate  flavor. 

The  canners  of  molasses  who  do  not  take  proper  care  of  the 
unrefined  molasses  will  experience  great  difficulty  in  preventing 
fermentation.  They  have  been  resorting  to  preservatives  as  a 
means  of  preventing  fermentation  and  overcoming  the  difficulties 
with  which  they  are  beset  through  careless  methods. 


72  CANNING  AND  PRESERVING   OF   FOOD   PRODUCTS. 


CHAPTER  III. 


Principles  of  Bacteriological  Technique 


Methods  of  Cultivating  Bacteria.  Artificial  Media.  Method 
of  Cultivating  Anaerobes.  Methods  of  Simple  Staining. 
Method  of  Staining  Flagella.  Method  of  Making  Photomi- 
crographs. 

When  foodstuff  is  attacked  by  bacteria  there  may  be  and  gen- 
erally are,  several  varieties  involved,  and  it  is  essential  that  these 
varieties  be  separated  and  studied  in  pure  cultures  under  all  con- 
ditions. If  the  canner  is  having  losses  from  swells  and  sour  goods, 
he  is  anxious  to  know  wdiat  is  the  cause;  the  preserver  has  mold 
appear  on  the  surface  of  his  jellies  and  preserves,  and  he  is  mysti- 
fied as  to  the  cause;  the  packers  of  corn  and  such  special  foods  as 
lobster,  and  fishballs,  find  the  contents  spotted  black  and  the  juices 
are  turned  dark,  and  the  mystery  deepens;  the  packers  of  meats 
and  fancy  soups  sometimes  receive  notice  of  ptomaine  poisoning, 
where  certain  cans  of  their  goods  are  held  responsible,  and  they 
are  totally  in  the  dark  as  to  the  cause;  bottlers  of  tomato  catsup 
suddenly  lose  a  large  per  cent,  of  their  goods,  where  every  detail 
of  the  work  seems  to  have  been  carried  on  as  in  former  years; 
picklers  are  surprised  to  find  soft  pickles,  where  their  old  and  tried 
methods  of  salting  have  been  followed  closely.  In  fact  there  is 
hardly  a  single  line  of  goods  but  that  shows  signs  of  spoilage  at 
certain  times  under  the  most  peculiar  circumstances.  Now  when 
this  spoilage  occurs  there  is  something  to  blame,  and  if  you  have 
carefully  watched  your  pack,  you  will  have  received  warning  of 
brewing  trouble.  A  can  will  swell  and  you  pick  it  up,  turn  it  over 
and  look  for  a  possible  leak ;  the  capping  and  tipping  are  smooth ; 
the  top  and  bottom  appear  all  right,  but  the  seam  looks  as  though 
there  might  be  a  leak,  and  you  pass  over  the  matter;  this  may  be 
a  warning  that  the  process  is  wrong,  and  if  you  let  the  matter  drop 
you  may  find  out  suddenly  that  a  large  per  cent,  of  your  goods  are 
going  wrong.  When  a  can  shows  signs  of  swelling  a  thorough 
bacteriological  examination  ought  to  be  made  at  once.  If  the  can 
is  only  a  leak,  there  wall  be  found  growino^  inside  various  germs, 
which  would  have  been  destroyed  in  a  single  boiling  process,  and 
this  would  be  fairly  conclusive  evidence  that  there  was  a  leak 
somewhere  in  the  can,  possibly  so  small  as  to  escape  the  most  rigid 
scrutiny.  If  the  can  is  a  swell  caused  by  an  underprocess,  the 
plate  culture  method  will  show  only  spore-bearing  species  of  bac- 


PRINCIPLES    OF   BACTERIOLOGICAL   TECHNIQUE.  73 

teria,  and  if  this  be  the  case,  the  process  must  be  examined  care- 
fully; first,  to  see  if  everything  is  in  good  working  order;  second, 
a  careful  test  of  thermometers  and  gauges ;  and  third,  to  see  if  the 
processor  is  giving  the  goods  the  required  time  and  temperature. 
If  all  these  are  found  to  be  correct,  then  cans  must  be  inoculated 
with  pure  cultures  of  the  bacteria  and  then  incubated  at  98° F.  If 
they  swell  they  show  insufficient  sterilization.  Sometimes  the  cans 
do  not  swell,  but  still  contain  germs,  which  will  decompose  the 
sugar  into  acid,  which  phenomenon  is  known  among  canners  as 
"sour  goods,"  so  it  is  well  to  cut  open  a  few  cans  and  streak  some 
Petri  dishes  containing  nutrient  agar  and  gelatin,  and  put  part  of 
these  in  the  anaerobic  culture  apparatus,  and  others  are  to  be  grown 
in  the  incubator,  covered,  but  allowing  circulation  of  atmosphere. 
Hanging  drops  of  the  liquid  in  the  cans  should  be  made  and  care- 
fully watched  under  a  1-12  oil  immersion  lens.  If  living  bacteria 
are  numerous,  they  may  be  seen  to  move  rapidlv  through  the 
fluid. 

Nearly  all  the  spore  bearing  bacteria  are  motile,  possessing,) 
usually,  numerous  flagella,  which  we  have  reproduced  in  various; 
photomicrographs  throughout  this  work.  As  we  have  previously' 
stated,  the  flagella  are  not  visible  when  examining  living  bacteria;! 
they  are  seen  only  after  staining  according  to  special  methods! 
which  we  will  describe  later  in  this  chapter.  ' 

The  preparation  of  nutrient  media  for  cultivating  bacteria  is 
essential  for  bacteriological  research  and  for  general  purposes  the 
following  formulae  are  used,  but  for  special  study  the  best  nutrient 
materials  are  made  with  the  fluids  of  such  goods  as  are  spoiling; 
for  instance,  the  bacteria  found  in  spoiled  peas  should  be  grown 
upon  the  sterilized  juice  of  peas,  or  if  it  be  spoiled  corn,  the  medium 
should  contain  as  a  base  the  filtered  sweet  corn  juice,  etc. 


ORDINARY   MEDIA. 

BOUILLON.  This  is  made  from  fresh  lean  meat  iuice  and  is 
used  generally  to  demonstrate  certain  peculiarities  of  various  species, 
to  differentiate  species,  and  aid  in  their  identification.  Sometimes 
the  bouillon  is  densely  clouded,  sometimes  only  slightly;  a  thick 
sediment  may  form,  and  this  precipitate  may  be  easily  diffused  by 
shaking,  or  may  be  too  heavy;  some  cultures  form  pellicles  or  skins 
over  the  surface,  and  these  may  be  easily  broken  (by  shaking  the 
tube)  or  may  be  very  tenacious.  The  indol  reaction  with  sulphuric 
acid  is  best  demonstrated  in  a  bouillon  culture.  Bouillon  is  an  ex- 
cellent medium  for  growling  the  various  germs  which  produce  pto- 
maines and  toxins;  the  germs  may  be  filtered  out  by  forcing  the 
liquid  through  a  porcelain,  or  Chamberland  filter,  and  the  analysis 
may  be  made  of  the  filtrate  for  such  poisons.     Bouillon  cultures 


74  CANNING  AND   PRESERVING   OP   FOOD   PRODUCTS. 

are  made  of  the  various  germs  whicli  are  used  in  agglutination 
tests,  described  under  Typhoid,  in  Chapter  V. 

FORMULA.  500  grammes  (about  17  ounces)  of  lean  beef 
are  cut  up  into  small  pieces ;  there  must  be  no  free  fat ;  the  meat  is 
covered  with  1,000  cubic  centimeters,  or  one  litre  (about  one 
quart),  of  distilled  water,  and  let  stand  in  refrigerator  24  hours. 
Squeeze  out  all  the  juice  possible  from  the  meat  and  strain  through 
flannel,  or,  better  still,  gently  simmer  over  flame  for  one  hour,  and 
then  strain.  The  flam^e  should  not  come  directly  in  contact  with 
the  bottom  of  the  enameled  pan,  so  a  sheet  of  asbestos  is  placed 
between  the  flame  and  the  pan  or  one  with  a  double  bottom  may 
be  used.  If,  after  this,  the  volume  is  short  of  1,000  c.c,  add 
enough  distilled  water  to  make  up  the  amount,  then  add  10  gram- 
mes of  Merck's  meat  peptone,  and  5  grammes  of  common  salt.  Put 
the  mixture  into  the  autoclav  or  process  retort  and  raise  the  tem- 
perature very  slowly  up  to  240° F.  and  hold  for  30  minutes;  after 
removing,  strain  through  four  thicknesses  of  flannel  and  let  stand 
until  cold,  then  filter  through  ordinary  filtering  paper.  Test  the 
bouillon  with  blue  litmus  paper  and  it  changes  the  color  to  red, 
which  shows  an  acid  reaction.  As  mosLbacteria  grow  better  on 
slightly  alkaline  media,  prepare  a  strong  solution  of  carbonate_of 
soda  and  -stir  into  the  bouillon,  just  enough  to  turn  red  litmus  pa- 
per slightly  blue.  Care  must  be  taken  not  to  add  too  much  alkali, 
for  in  the  preparation  of  agar  it  is  almost  impossible  to  obtain  a 
clear  filtrate. 

The  bouillon  is  now  a  beautiful  golden  color  and  clear.  A 
number  of  tubes  can  be  filled  about  one-fourth  full  and  the  balance 
filled  into  Florentine  flasks  for  future  use.  The  necks  must  be 
stuffed  with  tightly  twisted  absorbent  cotton,  and  all  the  tubes  and 
flasks  then  put  into  the  autoclav  and  sterilized  for  thirty  minutes 
at  240° F. ;  then  after  removing  they  must  be  kept  in  a  dark  place 
so  that  no  sunlight  shall  strike  them.  As  mentioned  in  last  chap- 
ter, strong  sunlight  will  cause  the  formation  of  dioxygen,  formalde- 
hyde and  traces  of  other  antiseptics,  through  the  oxidation  of 
sugars  and  fats. 

Dextrose  and  Milk  Sugar  Bouillon  may  be  made  by  adding  2 
per  cent,  of  either  to  the  bouillon.  This  combination  is  used  to 
demonstrate  biological  peculiarities  of  various  bacteria  towards 
sugar.  In  the  same  manner  and  for  the  same  purpose.  Glycerin 
Bouillon  is  made  by  adding  4  per  cent,  glycerin  to  ordinary  bouil- 
lon. Carbolic  acid  is  added  to  bouillon ;  6  per  cent,  of  a  5  per  cent, 
solution  of  carbolic  acid  will  retard  the  growth  of  undesired  bac- 
teria, and  is  used  in  the  isolation  of  certain  germs  found  growl- 
ing with  very  many  different  species,  which  under  ordinary  cir- 
cumstances grow  too  luxuriantly,  and  crowd  out  the  species  sought. 


PRINCIPLES   OF   BACTERIOLOGICAL   TECHNIQUE.  75 

SOLID    NUTRIENT    MEDIA. 

To  Dr.  Koch  of  Berlin  belongs  the  credit  of  this  vakiable 
discovery:  that  nutrient  bases  could  be  sohdified  in  gelatin  and 
agar-agar,  and  that  bacteria,  when  mixed  throtighout  the  mass, 
would  grow  and  form  colonies  of  their  own  kind,  and  would  not 
extend  very  far  (if  sufficiently  separated)  to  become  mixed.  By 
means  of  this  class  of  media  nearly  all  pure  cultures  are  obtained. 
If  Pasteur  had  taken  advantage  of  this  valuable  method  in  his  time, 
a  great  part  of  his  labors  would  have  been  made  easy,  and  the 
science  of  bacteriology  would  have  made  greater  progress  than  it 
has,  although  wonderful  discoveries  have  been  made,  yet  the  possi- 
bilities are  almost  unlimited.  Outside  of  electricity,  we  believe  that 
there  is  no  science  which  has  the  possibilities  that  lie  within  the 
ranee  of  the  bacterioloist.  There  are  a  number  of  diseases,  the 
cause  of  wdiich  is  still  mysterious,  there  being  no  definite  organism 
known  to  be  responsible;  there  are  smallpox,  scarlatina,  yellow 
fever,  foot  and  mouth  diseases,  rhinderpest,  syphilis,  and  many 
other  diseases  which  have  not  been  traced  positively  to  specific 
micro-organisms,  and  there  are  a  number  of  cases  of  spoilage  m 
foodstuffs  which  have  never  been  investigated,  so  that  we  cannot 
help  regretting  that  Pasteur  did  not  give  us  at  least  twenty  years 
advancement  by  using  solid  nutrient  media  in  his  time.  We  owe 
to  this  great  genius  much  of  our  present  knowledge,  but  how  much- 
more  he  might  have  discovered  with  solid  nutrient  media  to  facili- 
tate his  labor  is  only  a  matter  of  speculation. 

GELATIN  MEDIA.  Make  the  same  quantity  of  bouillon  as 
previously  given,  leaving  out  the  peptone  and  salt;  pour  over  this 
TOO  grammes  of  fine  gelatin,  lo  grammes  of  peptone,  and  5  gram- 
mes of  common  salt.  Dissolve  these  by  placing  pan  in  boiling 
water,  and  after  they  are  thoroughly  mixed  make  slightly  alkaline, 
as  directed  under  "bouillon."  Place  the  solution  in  the  filtering 
apparatus  (Novy's),  attach  suction  pump  and  filter,  or  filter  through 
four  thicknesses  of  flannel  if  you  have  no  other  means.  The  liquid 
is  then  poured  into  tubes  and  Florentine  flasks  stoppered  with  cot- 
ton and  sterilized  at  2I2°F.  for  one  hour  on  three  successive  days. 
If  it  is  desired,  Petri  dishes  may  be  placed  in  the  autoclav  and 
sterilized  at  the  same  time,  and  these  may  be  filled  with  the  gelatin 
medium.  When  sterilizing  Petri  dishes  I  have  found  it  wise  to 
turn  both  tops  and  bottoms  upside  down  in  wire  basket,  which 
prevents  the  accumulation  of  condensed  water,  so  undesirable.  The 
gelatin  will  harden  if  placed  in  a  temperature  below  75 °F.,  so  the 
best  method  is  to  place  it  in  a  refrigerator.  Since  gelatin  melts  at 
about  75  °F.,  it  cannot  be  used  advantageously  in  hot  weather,  but 
in  cold  weather  is  advantageous,  because  it  is  very  clear,  is  easily 
prepared,  and  the  colonies  of  bacteria  grown  on  it  have  more  char- 
acteristic peculiarities  than  on  agar. 


76  CANNING   AND   PRESERVING   OF   FOOD    PRODUCTS. 

Special  preparations  may  be  made  with  gelatin  by  adding- 
grape  sugar,  milk  sugar,  glycerin  or  carbolic  acid,  as  directed  un- 
der "bouillon." 

Solid  culture  media  can  be  made  by  using  gelatin  with  the 
juices  of  fruits,  vegetables  and  the  liquid  or  special  food  prepara- 
tions.    Usually  lo  per  cent,  gelatin  will  be  found  sufficient. 

These  special  gelatin  preparations  have  great  value  in  the 
study  of  food  spoilage,  because  the  organisms  in  pure  cultures  will 
produce  the  very  changes  so  often  observed  in  spoiled  canned  goods, 
while  in  the  regular  meat  juice  gelatin  these  special  characteristics 
may  not  be  re\'ealed. 

For  the  cultivation  of  the  heat  loving  bacteria,  the  lactic  group, 
and  many  pathogenic  species,  gelatin  is  not  very  satisfactory,  since 
it  cannot  be  incubated,  but  for  the  demonstration  of  liquefying  bac- 
teria it  is  fine,  and  furnishes  means  of  differentiating  species,  where 
ag^ar  and  even  blood  serum  fail  to  reveal  this  characteristic. 


AGAR -AGAR   MKDFA. 

AGAR- AGAR  is  prepared  from  a  seaweed  which  grows  on 
the  coast  of  China  and  Japan,  and  is  used  in  the  place  of  gelatin, 
over  which  it  has  many  advantages.  It  is  more  difficult  to  prepare, 
however,  and  considerable  time  and  care  must  be  given  it  to  pro- 
duce a  good  clear  medium.  Formula:  The  meat  juice  is  prepared 
as  directed  under  the  head  of  "Bouillon,"  and  lo  grammes  of  pep- 
tone and  5  grammes  of  salt  are  added,  as  directed  under  "Gelatin," 
but  instead  of  gelatin  i  to  2  per  cent,  agar  is  used.  The  agar  is  cut 
up  quite  fine,  and  thoroughly  washed  after  being  weighed.  Place 
the  pan  in  the  autoclav  and  slowly  raise  the  temperature  to  240°  F., 
maintaining  same  for  about  10  minutes ;  then  lower  the  pressure 
and  filter  the  fluid  through  Novy's  agar  apparatus,  having  previous- 
ly made  the  lif[Uor  slightly  alkaline  with  sodium  carbonate  solution, 
using  great  care  not  to  add  too  much  to  avoid  cloudiness.  Novy's 
apparatus  gives  a  clear,  golden  filtrate,  which  is  beautifully  trans- 
parent after  solidification.  Flasks  and  tubes  are  filled  as  directed 
under  ''Gelatin,"  and  these,  with  the  desired  number  of  Petri  dishes, 
are  placed  in  the  autoclav  and  sterilized  at  240° F.  for  35  minutes. 
The  agar  does  not  solidify  until  the  temperature  falls  to  I02^F., 
and  the  tubes  may  be  slanted  by  laying  them  down  so  that  the  liquid 
agar  will  flow  up  towards  the  cotton  pretty  well ;  by  raising  the 
mouth  of  the  tube,  any  desired  slant  may  be  obtained.  The  Petri 
dishes  are  filled  while  the  agar  is  still  hot.  There  is  always  con- 
siderable condensation  water  left  on  the  surface  of  solidified  agar, 
and  to  minimize  this  the  temperature  of  the  dishes  should  be  about 
the  same  as  that  of  the  agar  wdien  it  is  poured  out.  After  agar 
has  solidified  it  does  not  melt  again  except  at  high  temperature. 


PRINCIPLES   OF   BACTERIOLOGICAL  TECHNIQUE.  77 

thus  it  has  the  advantage  over  gelatin,  in  that  it  may  be  kept  at 
blood  temperature  in  the  incubator.  There  are  a  number  of  bac- 
teria which  require  this  temperature  for  characteristic  growth.  Agar 
is  the  best  medium  for  growing  motile  bacteria  which  are  to  be 
stained  to  demonstrate  their  flagella.  Bacteria,  when  grown  on 
gelatin  or  in  fluids,  carry  with  them  so  much  of  the  medium  upon 
which  they  are  growing  that  the  flagella  cannot  be  stained  properly. 

Various  combinations  of  agar  are  made  for  special  cultures, 
such  as  those  described  under  "Gelatin."  Chemicals,  such  as  sac- 
charate  of  iron  or  tartrate  of  iron,  may  be  added  to  agar  to  demon- 
strate the  production  of  sulphuretted  hydrogen  by  certain  species 
of  bacteria;  lactose  and  sterilized  litmus  tincture  are  sometimes 
added  to  demonstrate  the  ability  of  certain  species  to  cause  fer- 
mentation of  lactose  and  the  production  of  acids.  Agar  may  be 
streaked  with  sterilized  blood  to  cultivate  special  bacteria.  In  fact 
agar  is  the  best  nutrient  medium  for  general  purposes. 

POTATO  MEDIA.  The  growth  of  many  species  of  bacteria 
on  potato  is  often  of  great  value  in  assisting  the  bacteriologist  to 
identify  them.  Owing  to  the  very  resistant  forms  of  germ  life 
found  naturally  on  potatoes,  it  is  difficult  to  prepare  sterile  media. 
There  are  three  varieties  of  bacteria  found  growing  on  the  surface 
which  will  withstand  considerable  boiling  to  destroy  the  spores; 
they  are  Mesentericus  vulgatus,  Mesentericus  fuscus  and  ]\Iesenter- 
icus  ruber,  the  spores  of  the  latter  being  able  to  withstand  six  to 
ten  hours'  boiling.  To  prepare  potatoes,  they  must  be  thoroughly 
washed  in  water  and  the  eyes  removed,  then  sterilized  in  the  auto- 
clav  for  fifteen  minutes  at  240° F.  Before  they  are  removed,  the 
hands  should  be  washed  in  a  bi-chlorid  of  mercury  solution,  i  to 
1,000,  and  a  sterilized  knife  may  be  used  to  cut  the  potatoes  in 
halves  lengthwise.  Place  the  pieces,  cut  side  up,  in  culture  dishes 
having  filter  paper  in  the  bottoms.  The  filter  paper  should  be  w^et 
with  the  mercury  solution,  to  prevent  contamination.  The  surface 
of  the  potato  may  then  be  streaked  with  the  pure  culture  of  the 
bacteria.  This  work  may  be  simplified  by  cutting  the  potatoes  into 
slices  and  sterilizing  in  autoclav  for  twenty  minutes  at  250°F.,  and 
then  transferring  into  sterile  Petri  dishes. 

Potato  juice  may  be  combined  with  agar  iVi  per  cent.,  or 
gelatin  10  per  cent.,  and  a  small  quantity  of  i  per  cent,  solution 
iodide  of  potassium,  and  sterilized  thirty  minutes  at  240°F.  This 
is  an  excellent  medium  for  growing  the  typhoid  bacilli,  because  it 
is  slightly  acid,  and  the  bacilli  form  threads  which  have  a  beautiful 
serpentine  movement. 

MILK  MEDIA.  Milk  is  used  to  demonstrate  the  power  of 
coagulation  of  certain  bacteria,  also  to  show  whether  they  produce 
acids  or  alkalis,  or  whether  their  action  is  amphoteric.  Milk  is 
difficult  to  sterilize,  owing  to  the  presence  of  spore-bearing  bacteria, 


78  CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 

which  are  very  resistant  to  heat.  Too  much  heat  changes  the 
chemical  composition  of  milk,  so  that  ^vhen  boiled  at  2I2°F.,  citrate 
of  lime  is  deposited  or  precipitated,  and  there  are  formed  such 
antiseptics  as  formaldehyde  and  peroxid  of  hydrogen.  The  milk 
fresh  from  the  cow,  taken  under  aseptic  precautions,  is  best,  be- 
cause it  may  thus  be  obtained  almost  free  from  bacteria.  Fill  the 
milk  into  sterile  tubes,  plug  them  with  cotton,  and  heat  to  i6o°F. 
for  one  hour  for  five  successive  days,  keeping  same  always  in  a 
temperature  not  to  exceed  70^ F. 

Tincture  of  litmus  added  to  milk  until  slightly  blue,  before  ster- 
ilizing, is  very  useful  in  determining  the  acid  producing  power  of 
certain  species  of  bacteria.  The  formation  of  acid  will  change 
the  color  to  pink  or  red. 

For  most  purposes,  milk  put  into  test  tubes  and  sterilized  for 
fifty  minutes  at  250°F.,  will  prove  satisfactory;  the  chemical  alter- 
ations are  not  so  great  as  to  interfere  with  the  study  of  non-patho- 
genic bacteria.  Milk  is  not  a  good  medium  for  growing  bacteria, 
except  for  the  purpose  indicated,  because  it  is  not  transparent  and 
if  solidified  by  adding  gelatin  or  agar  and  used  for  plate  cultures, 
the  colonies  of  bacteria  are  very  hard  to  find.  The  milk  may  be 
coagulated,  however,  and  the  clear  fluid  used  with  peptone  and 
salt  and  solidified  with  10  per  cent,  gelatin,  or  2  per  cent,  agar,  and 
have  value  in  the  cultivation  of  bacteria  associated  with  milk. 

BLOOD  SBRUM.  This  nutrient  medium  is  valuable  for 
growing  various  germs  which  produce  ptomaines  and  toxins.  The 
power  of  liquefying  solidified  serum  is  useful  for  identification  of 
species.  The  blood  is  taken  from  the  animal  under  aseptic  precau- 
tions and  allowed  to  stand  one  day  in  refrigerator,  when  the  serum 
may  be  drawn  off  and  filled  into  tubes.  The  serum  will  be  sterile 
if  due  care  has  been  exercised.  Tubes  of  serum  may  be  sterilized 
in  Koch's  blood  serum  sterilizer  one  hour  at  I50°F.  for  five  suc- 
cessive days.  They  may  be  solidified  in  Koch's  apparatus  for  soli- 
difving  blood  serum  by  heating  to  I70^F. 

'  BREAD  MBDIA  FOR  CULTIVATING  MOLDS.  Bread, 
when  made  moist,  is  acid  in  reaction,  and  is  a  nutrient  medium  for 
molds ;  bacteria  do  not  grow  well  on  acid  media,  so  the  isolation  of 
various  species  of  Hyphomiycetes  is  made  easier,  because  acid  is 
favorable  for  their  growth.  Fine  bread  crumbs  are  collected  in 
the  bottoms  of  several  test  tiibes  and  sterilized  water  is  added,  suffi- 
cient to  make  a  paste.  The  tubes  are  sterilized  by  boiling  for  three 
successive  days  at  2i2°F.  for  fifteen  minutes. 

METHOD   Ot"   MAKING    CULTURES. 

In  order  to  determine  the  different  species  of  bacteria  which 
are  causing  spoilage  or  disease,  it  is  necessary  to  separate  them  one 
from  another  and  study  them  in  pure  cultures.     It  rarely  happens 


PRINCIPLES    OF   BACTERIOLOGICAL  TECHNIQUE.  79 

that  one  species  is  found  alone;  there  are  usually  various  kinds  of 
bacteria  growing  together,  and  to  separate  them  requires  careful 
manipulation,  which  is  easily  accomplished  by  practice,  and  aseptic 
precautions.  If  we  desire  to  cultivate  the  various  bacteria  found  in 
a  can  of  sour  goods,  we  proceed  as  follows :  A  bunsen  flame  is 
forced  down  on  to  the  surface  of  the  tin,  and  a  sterilized  awl  is  put 
into  the  flame  and  pushed  throtigh  the  tin;  if  any  air  is  sucked  into 
the  can  by  a  vacuum,  it  is  sterilized  in  the  flame  which  covers  the 
hole;  a  long  platinum  looped  wire  is  then  heated  to  incandescence 
and  put  down  into  the  can  through  the  hole  and  quickly  with- 
drawn, and  the  loopful  of  material  is  transferred  to  liquefied  gelatin 
and  agar  tubes  and  dishes,  previously  prepared  as  follows :  The 
gelatin,  tubes  are  liquefied  in  warm  water,  and  after  singeing  the 
cotton  plug  in  the  flame,  tube  No.  i  is  inoculated  by  holding  tube 
in  slanting  position  in  left  hand,  removing  cotton  plug  with  little 
finger  of  right  hand,  and  then  rubbing  up  the  loopful  of  material 
on  one  side  of  the  tube,  mixing  it  with  the  gelatin ;  the  plug  is  then 
put  in  and  the  gelatin  mixed  thoroughly  by  rolling  and  gentle  shak- 
ing. The  platinum  loop  is  then  sterilized  in  flame  and  tube  No.  2 
is  inoculated  from  No.  i,  both  being  held  in  a  slanting  position  in 
left  hand  and  the  plugs  of  each  removed  in  succession  with  little 
finger  of  right  hand.  Two  or  three  loopfuls  of  gelatin  from  No.  i 
are  transferred  to  No.  2,  and  the  plugs  replaced ;  the  gelatin  in  No. 
2  is  then  shaken,  the  platinum  loop  sterilized  as  before,  and  in  the 
same  manner  tube  No.  3  is  inoculated  with  two  or  three  loopfuls 
from  No.  2.  After  shaking  and  mixing  thoroughly,  all  three  are 
poured  into  sterilized  Petri  dishes  and  placed  in  refrigerator  or  on 
ice  to  solidifv  the  gelatin,  after  which  they  are  maintained  at  about 
70°F. 

In  like  manner  a  number  of  tubes  are  inoculated  and  placed 
in  the  anaerobic  culture  apparatus  after  chilling.  It  usually  hap- 
pens that  No.  I  and  No.  2  have  too  many  colonies,  which  cannot 
successfully  be  separated  before  they  grow  together,  but  No.  3  usu- 
ally contains  but  few  colonies,  which  may  be  studied  carefully  as  to 
color,  shape,  size  and  border,  also  the  liquetaction  of  gelatin,  if  any 
occurs.  Observations  must  be  made  and  noted  of  their  appearance 
in  natural  size,  then  of  their  appearance  under  various  magnifica- 
tions. 

Agar  plate  or  Petri  dish  cultures  are  made  in  the  same  man- 
ner, except  that  the  agar  is  melted  first  in  autoclav  at  240° F.,  and 
then  poured  into  tubes.  The  agar  solidifies  at  I02°F.,  so  this  mtist 
be  borne  in  mind  and  the  work  must  be  done  quickly,  at  about 

I20°F. 

Gelatin  is  difficult  to  manipulate  in  hot  weather,  and  cannot 
be  incubated,  so  it  is  advisable  to  make  cultures  on  agar  as  well 
as  gelatin.     The  writer  has  been  successful  in  isolating  the  various 


80  CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 

species  in  Petri  dishes  alone,  without  using  the  tubes,  as  follows : 
The  agar  is  liquefied  and  poured  into  the  sterilized  dishes,  and  just 
before  it  begins  to  harden  transfers  are  made  by  mixing  a  loopful 
of  the  suspected  material  in  dish  No.  i,  using  a  long  platinum  loop- 
ed wire  and  holding  the  lid  of  the  dish  up  from  the  edge  just  high 
enough  to  permit  thorough  mixing.  By  a  gentle  swaying  motion 
the  mixing  can  be  made  uniform.  Transfers  are  then  made  to  a 
second  and  a  third  dish,  as  described  in  method  of  inoculating 
tubes,  the  platinum  loop  being  sterilized  between  each  transfer.  Dish 
No.  I  will  usually  have  too  many  colonies,  which  will  grow  to- 
gether before  they  are  old  enough  to  show  special  characteristics; 
No.  2  may  be  better,  but  No.  3  w^ill  probably  contain  but  few 
colonies,  which  may  be  carefully  studied  and  transfers  made  to  new 
dishes,  which  are  streaked  by  pushing  a  sterilized  platinum  loop 
into  a  colony  (or  if  the  colony  is  very  small,  a  needle  is  better), 
and  the  surface  of  the  new  dish  is  streaked  by  simply  drawing  the 
wire  over  the  surface.  Some  care  is  required  in  handling  Petri 
dishes;  if  .there  be  any  water  of  condensation  either  on  the  surface 
of  the  agar  or  on  the  under  side  of  the  cover,  it  should  be  set  to 
one  side  and  not  used  until  this  evaporates.  Freshly  made  agar 
usually  has  considerable  water  of  condensation  and  it  is  well  to  use 
only  that  which  has  stood  in  flasks  long  enough  to  show  only  slight 
traces,  although  dishes  may  be  filled  with  fresh  agar  and  allowed 
to  stand  until  the  surface  is  dry  and  no  drops  of  water  are  visible 
on  the  under  surface  of  the  cover. 

When  material  under  investigation  contains  only  a  few  scat- 
tered bacteria,  which  may  be  ascertained  by  examination  of  hang- 
ing drops,  Petri  dishes  may  be  streaked  without  the  necessity  of 
liquefying  the  agar;  the  loop  is  sterilized  and  plunged  into  the  ma- 
terial and  the  surface  of  several  dishes  streaked  without  sterilizing 
the  platinum  during  the  inoculations.  The  first  one  or  two  may 
not  he  freely  distributed,  but  others  will  contain  colonies  here  and 
there  which  are  pure  cultures,  and  these  may  be  transferred  to  fresh 
dishes.  Pure  cultures  will  remain  alive  for  months,  and  in  some 
cases  for  years,  in  test  tubes  sealed  and  protected  wnth  rubber  caps, 
or  if  plugged  with  sterilized  cotton  and  sealed  with  wax  (having 
previously  moistened  the  surface  of  the  cotton  with  corrosive  subli- 
mate.) Mold  destro3^s  many  cultures;  it  starts  to  grow  in  the  cot- 
ton and  will  often  grow  through  it,  down  along  the  inside  of  the 
tube  for  several  inches,  until  it  reaches  the  nutrient  material.  It  is 
well  to  make  fresh  transfers  of  cultures  which  are  desired  to  be 
kept,  at  least  once  in  three  weeks. 

As  it  is  necessary  to  cultivate  bacteria  in  the  absence  of  oxygen, 
a  special  apparatus  is  desirable,  one  employed  for  such  purpose  (by 
Novy)   is  worthy  of  special  mention,  since  it  may  be  used  with 


PRINCIPLES   OF   BACTERIOLOGICAL.   TECHNIQUE. 


81 


hydrogen  or  the  pyrogaUate  method  for  both  tube  and  plate  cul- 
tures. 

For  very  fine  work,  hydrogen  is  preferable  to  any  other  gas 
for^  anaerobic  cultures,  for  the  reason  that  other  gases  permeate 
the  culture  media  to  a  certain  extent  and  have  some  influence  on 
the  growth  of  delicate  organisms.  The  cost  and  trouble  connected 
with  this  method  are  too  great  for  ordinary  work,  so  the  pyrogal- 
late  method  is  generally  employed,  which  may  be  described  as  fol- 
lows :  The  test  tubes  are  put  into  apparatus  in  upright  position  on  a 


Fig.  28 


wire  rest,  which  fits  in  glass  cylinder  about  two  inches  above  the 
bottom;  on  this  wire  the  Petri  dishes  may  be  placed  also;  before 
sealing,  a  quantity  of  pyrogallic  acid  and  a  1-16  dilution  of  normal 
potassium  hydroxid,  or  caustic  potash,  are  put  into  the  bottom  of 
the  apparatus  so  that  the  liquid  will  be  a  litle  over  one  inch  deep. 
The  pyrogallate  formula  is,  one  part  pyrogallic  acid  and  ten  parts 
of  a  1-16  normal  caustic  potash  solution.  (A  normal  solution  con- 
tains about  seven  grammes  to  125  cubic  centimeters  of  water.)  The 
apparatus  must  be  sealed  quickly,  and  the  glass  stop-cock  at  the  top 
shut  off,  so  that  there  will  be  a  complete  absorption  of  the  oxygen 
within  the  chamber.  The  apparatus  may  be  placed  in  the  incubator 
or  may  be  left  at  room  temperature,  according  to  the  nature  of  the 
organisms  under  investigation.  In  this  manner  it  may  be  demon- 
strated if  a  given  species  of  bacteria  is  strictly  anaerobic  or  whether 
it  is  facultative  anaerobic. 

In  canned  goods  which  have  soured,  there  are  frequently  found  i 
strictly  anaerobic  bacteria  growing  along  with  other  species  which  \ 
are  aerobic  by  nature.     The  can  contains  oxygen  after  every  ster-  ' 
ilizing  process,  and  this  oxygen  is  used  up  by  the  aerobic  bacteria, 
and  then  the  anaerobic  varieties  begin  to  grow,  where  the  steriliza- 
tion has  not  been  complete.     This  is  a  common  phenomenon  and 
explains  our  failures  sometimes  in  isolating  living  bacteria  from 
cans  of  sour  goods,  where  the  anaerobic  apparatus  is  not  employed. 
In  the  natural  putrefactive  processes  going  on  in  the  free  atmos- 


82  CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 

1  phere  the  anaerobic  bacteria  depend  upon  the  aerobes  to  use  up  all 

/  the  oxygen,  while  they  remain  dormant  until  there  is  a  favorable 

'  condition  of  environment  for  their  growth. 

STAINING. — When  living  bacteria  are  viewed  through  the 
microscope,  in  order  to  see  them  well,  a  1-12  oil  immersion  lens 
must  be  used  and  the  result  is  not  very  satisfactory  so  far  as  the 
size  and  general  characteristics  are  concerned.  If  the  bacteria  are 
motile  this  may  be  learned,  but  it  is  hard  to  follow  an  actively 
motile  bacillus,  for  it  is  in  focus  usually  only  an  instant,  and  then 
it  is  necessary  to  use  the  fine  adjustment  to  bring  it  into  focus 
again,  which  often  fails.  Non-motile  organisms  are  clumped  usu- 
ally, but  owing  to  the  great  transparency  of  bacteria  the  study  of 
the  living  unstained  germs  is  not  very  satisfactory. 

The  art  of  staining  has  enabled  the  bacteriologist  to  deter- 
mine in  many  instances  the  kind  and  class.  Many  bacteria  have 
peculiarities  in  their  staining  properties,  and  these  peculiarities  help 
the  student.  There  are  certain  staining  methods  which  fail  with 
some  species  and  the  staining  of  flagella  often  aids  the  worker  in 
determining  the  species  by  the  number  and  character  of  the  flagella 
of  motile  organisms.  There  are  some  motile  bacteria  which  seem 
to  possess  no  flagella,  and  it  is  thought  that  their  motility  is  achiev- 
ed by  an  undulating  membrane  attached  to  them,  (I  have  never 
seen  any  motile  bacilli  without  flagella),  and  the  absence  of  flagella 
from  the  cell  of  a  motile  organism  can  be  ascertained  only  by  nega- 
tive results  in  staining.  Some  bacteria  are  surrounded  by  a  cap- 
sule, which  is  brought  out  by  staining.  Spores  are  easily  located 
within  the  cells  by  their  resistance  to  staining;  the  cell  stains  well, 

(but  leaves  the  bright  spore  almost  transparent  within  the  cell  mem- 
brane. The  spores  themselves  are  stained  by  special  methods  and 
the  rest  of  the  rod  may  be  stained  with  a  different  colored  dye, 
which  produces  a  beautiful  effect  in  permanent  mounts. 

The  first  step  in  staining  is  to  have  clean  cover-glasses  (cover- 
glasses  are  either  round  or  square  pieces  of  glass  only  about  i-ioo 
to  1-200  of  an  inch  thick,)  which  are  sold  in  small  boxes  holding 
half  an  ounce.  The  cover-glasses  are  covered  usually  with  a  fatty 
substance,  which  is  removed  with  difficulty.  This  fat  is  removed 
by  soaking  a  number  in  sulphuric  acid  for  a  day  or  two,  then  wash- 
ing with  caustic  soda  or  potash,  and  then  further  cleaned  by  a  mix- 
ture of  alcohol  and  ammonia.  (See  also  method  of  cleaning  cover- 
glasses  described  under  flagella  staining).  It  is  well  to  keep 
cover-glasses  in  absolute  alcohol  in  a  bottle  with  ground  glass  stop- 
per to  avoid  evaporation.  Just  before  using  they  are  lifted  out  of 
the  alcohol  one  at  a  time,  and  dried  with  clean  linen  free  from 
fat,  then  passed  quickly  throus^h  a  flame.  If  allowed  to  get  too 
hot  the  edges  melt  down  or  the  shape  changes  either  concave  or 
convex,  which  is  undesirable,  or  the  glass  flies  all  to  pieces,  which 


PRINCIPLES   OF   BACTERIOLOGICAL   TECHNIQUE.  83 

is  often  the  case,  but  may  be  overcome  by  quick  work.  A  small 
drop  of  distilled  water  is  placed  in  the  center  of  the  glass,  and  a 
small  speck  of  material  containing  germs  is  mixed  with  the  drop, 
care  being  taken  net  to  have  too  many  germs;  the  drop  is  then 
evenly  spread  over  the  whole  surface,  and  if  the  glass  be  clean  this 
will  be  done  easily.  Should  the  fluid  collect  in  small  droplets,  it 
indicates  that  the  cover-glass  is  not  clean,  and  the  process  of  clean- 
ing the  cover-glass  must  be  gone  over  again  so  that  the  fluid  will 
spread  evenly  over  the  entire  surface.  For  convenience  in  handling, 
the  cover-glass  is  held  in  a  small  forceps.  (One  devised  by  Novy 
for  this  purpose  is  very  good.)  The  fluid  is  allowed  to  dry  onto 
the  glass  by  evaporation,  or  may  be  hastened  by  waving  in  the 
air.  When  absolutely  dry  it  is  fixed  by  passing  through  the  Bunsen 
flame  three  times  quickly,  keeping  specimen  side  away  from  actual 
contact  with  the  flame.  The  bacteria  are  thus  firmly  fixed  on  the 
glass,  so  that  they  will  not  wash  away  when  the  staining  is  done. 
A  small  drop  of  water  is  then  placed  on  the  specimen  side,  and  al- 
lowed to  spread  over  the  surface,  and  then  the  glass  is  flooded 
with  an  aqueous  solution  of  dye,  such  as  carbol  fuchsin,  methylene 
blue,  gentian  violet,  Bismarck  brown,  etc.  The  glass  holding  the 
rounded  drop  of  color  is  held  about  three  inches  over  the  flame 
and  heated  until  vapor  is  seen  to  rise,  and  this  is  maintained  for 
several  minutes,  care  being  exercised  to  avoid  actual  ebullition.  It 
is  not  a  good  plan  to  force  the  staining  by  too  much  heat ;  the  best 
results  are  obtained  by  gentle  heating  for  a  longer  time,  and  if 
the  stain  is  allowed  to  cool  before  using  water  to  wash  excess 
away,  the  danger  of  celT  shrinkage  is  minimized.  After  washing 
off  the  excess  of  stain,  a  few  drops  of  diluted  alcohol  will  clear 
up  the  field,  but  it  must  be  washed  off  at  once;  then  take  a  clean 
glass  slide  and  place  the  cover-glasses  on  it,  specimen  side  down, 
removing  excess  of  water  by  filter  paper,  and  dry  the  upper  sur- 
face ;  now  place  a  small  drop  of  cedar  oil  on  center  of  cover-glass ; 
put  slide  under  microscope;  bring  down  1-12  objective  until  it 
touches  the  oil  and  bring  into  focus  with  fine  adjustment.  If  the 
s])ecimen  Is  all  right  the  cover-elass  may  be  floated  off  by  water 
and  allowed  to  dry  in  air  or  by  touching  edge  to  filter  paper,  wav- 
ing in  air,  etc.,  and  when  dry  it  may  be  cleared  by  flooding  both 
sides  with  xylol,  then  turned  edge  down  on  filter  paper  and  finally 
held  about  twelve  inches  above  flame  until  dry.  To  mount  cover- 
glass,  take  a  clean  slide,  warm  over  flame  until  all  moisture  is 
forced  away,  then  place  a  small  drop  of  Canada  balsam  dissolved 
in  xylol  in  the  center.  (Xylol  balsam  is  put  up  in  tubes  all  pre- 
pared for  use.  A  small  drop  may  be  sqtieezed  out  of  the  tube  onto 
the  slide,  experience  teaching  just  the  required  amount.)  The 
slide  is  again  held  over  flame  to  drive  away  all  mosture,  and  the 
cover-glass  is  also  warmed  and  placed,  specimen  side  down,  upon 


84  CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 

the  drop  of  balsam,  and  may  be  pressed  down  firmly  by  laying  a 
sheet  of  filter  paper  over  it,  or  by  using  a  cork  of  the  same  diameter. 
There  should  be  only  enough  balsam  to  fill  up  space,  but  it  often 
happens  that  some  excess  will  be  squeezed  out;  this  will  harden 
eventually  and  will  cause  no  inconvenience  unless  it  is  too  excessive, 
in  which  case  it  may  be  removed  with  a  little  xylol  and  clean  linen. 
Many  microscopists  have  trouble  in  obtaining  clear  work  on 
account  of  moisture  on  the  slide  or  cover-glass  during  the  mounting, 
so  I  wish  to  call  particular  attention  to  the  perfect  drying  of  both 
slide  and  cover-glass  before  using  the  xylol  for  clearing. 

METHOD  OP  OBTAINING  AND  STAINING  CONTACT 
SPECIMENS.— This  method  is  used  to  show  the  "Swarming  Is- 
lands" of  such  bacteria  as  Proteus  Vulgaris,  Proteus  Mirabilis  and 
Proteus  Zenkeri,  which  are  shown  in  plates. 

The  colonies  are  grown  on  gelatin,  and  when  the  bacilli  begin 
to  swarm  and  branch  off  from  the  parent  colony  a  cover-glass  is 
dropped  carefully  over  a  colony  and  gently  pressed;  it  is  then 
lifted  straight  up,  avoiding  any  lateral  movement,  and  dried  in  the 
air,  then  stained  as  directed  in  the  ordinary  method.  If  the  colonies 
show  liquefaction,  contact  specimens  cannot  be  made. 

gram's  method  of  staining. 

This  method  of  staining  is  used  to  differentiate  the  species. 
There  are  a  great  many  bacteria  wdiich  do  not  retain  the  stain, 
while  others  having  great  resemblance  take  the  stain  readily.  The 
age  of  the  culture  and  the  medium  upon  which  it  grows  have  some- 
thing to  do  with  the  results. 

METHOD. 

1.  The  cover-glass  specimen  is  stained  for  a  few  minutes  with 
Ehrlich's  anilin-water  gentian  violet.  (Anilin  oil^4  c.c.+ water 
lOO  c.c.+ii  c.c.  of  concentrated  alcohol  solution  of  gentian  violet.) 

2.  Wash  with  water  and  use  Gram's  solution  of  iodin  (iodin 
crystals  i  gramme -f- iodide  of  potash  2  grammes + water  300  c.c.) 
until  the  stained  surface  blackens,  which  requires  about  half  a  min- 
ute. 

3.  Wash  with  alcohol  until  excess  color  is  removed.  Then  the 
specimen  may  be  examined  under  the  microscope  to  ascertain  if 
the  bacteria  have  taken  the  stain. 

METHOD  OF   STAINING  TUBERCLE   BACILLI. 

The  tubercle  bacilli  are  found  frequently,  and  often  in  large 
numbers,  in  fresh  milk  and  also  in  butter.  The  method  of  staining 
here  given  is  used  to  demonstrate  the  bacilli  from  phthisical  pati- 


PRINCIPLES    OF   BACTERIOLOGICAL   TECHNIQUE.  85 

ents  and  is  applied  to  the  sputum,  which  is  carefully  spread  over 
the  surface  of  a  cover-glass,  air  dried  and  fixed  in  flame  as  in  ordi- 
nary method.  Tubercle  sputum  is  easily  obtained,  and  the  stain- 
ing of  the  bacilli  affords  excellent  practice  for  the  beginner. 

P'or  examining  milk  and  butter  a  centrifugal  machine  is  used 
to  obtain  a  sediment,  which  is  more  apt  to  show  the  presence  of 
consumption  germs  than  a  small  quantity  taken  at  random. 

The  suspected  milk  is  put  into  the  bottles  and  the  machine  is 
used  for  a  few  minutes,  the  fluid  is  poured  oft'  and  the  cover-gla^s 
is  spread  with  some  of  the  sediment.  If  butter  be  suspected,  a 
small  quantity  is  put  into  a  test  tube  about  three-fourths  full  of 
water,  w^hich  is  then  heated  in  water  to  melt  the  fat.  The  tube  is 
thoroughly  shaken  and  put  on  ice  to  solidify  the  fat,  after  which 
the  fluid  is  put  into  the  centrifugal  machine,  the  same  as  described 
for  milk,  and  a  cover-glass  spread  is  made  of  the  sediment.  The 
cover-glass  thus  prepared  w\\\  contain  too  much  fat,  so  it  must  be 
air  dried  and  heated  slightly,  and  laid  in  a  mixture  of  ether  and 
alcohol  ( I  to  3)  for  a  few  seconds,  then  removed,  air  dried,  fixed 
in  flame  and  stained  as  follows : 

The  cover-glass  is  flooded  with  Ziehl-Neelsen's  carbol-fuchsin 
(fuchsin  I  gramme+alcohol  10  c.c.+water  100  c.c. -{-carbolic  acid 
5  grammes),  and  heated  over  flame  until  vapor  arises  and  set  to 
one  side.  Repeat  three  or  four  times ;  w^ash  off  excess  of  stain  with 
water  and  decolorize  with  a  twenty  per  cent,  solution  of  sulphuric 
acid  and  wash  acid  off  with  water.  If  still  too  red,  use  sulphuric 
acid  again.  When  washed  the  specimen  should  be  pink.  The 
cover-glass  is  then  flooded  with  Loeffler's  methylene  blue  (concen- 
trated alcohol  solution  of  methylene  blue  30  c.c.+ watery  solution 
of  caustic  potash  1:10,000 — too  c.c),  and  heated  for  a  few  sec- 
onds, then  washed  under  the  water  tap  until  all  excess  color  is  re- 
moved. The  tubercle  bacilli  will  be  stained  a  deep  red,  and  the 
surrounding  field  will  be  blue,  which  makes  a  beautiful  contrast. 

Since  one-seventh  of  the  population  of  the  world  die  from  con-(l 
sumption,  this  disease  germ  is  most  interesting  for  study  and  bac-i 
teriological  investigation.     It  is  transmitted  from  one  person  to  an-|| 
other  in  various  ways,  by  breathine  particles  of  floating  matter 
containing  the  bacilli  in  the  homes  of  consumptives,  in  public  con-| 
veyances  and  buildings,  and  in  articles  of  food,  such  as  milk  and: 
butter.     It  is  not  hereditary.     The  germs  are  destroyed  at  2i2°F.,^'i 
and  there  is  dano-er  only  in  such  foods  as  are  consumed  in  an  un-  j 
cooked  state.     Pasteurization  destroys  them  in  milk,  and  this  meth-; 
od  of  treatins:  milk  and  cream  intended  for  butter-making  is  to  beM 
highly  commended. 


CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


Bacillus  Tuberculosis,  Koch  (1882) 

TUBERCLE    BACILLUS. 

Origin. — In  tuberculosis  of  mammals;  in  lupis  vulgaris.  The  bacillus 
of  chicken  tuberculosis  is  distinct  from  that  of  mammals. 

Form. — Rather  long,  very  narrow  rods,  srnaller  than  the  diameter  of 
a  blood  cell.  Are  sometimes  beaded.  May  be  straight,  but  more  fre- 
quently are  slightly  bent  or  nicked;  distinctly  rounded  ends.  Usually 
single,  but  sometimes  forms  short  threads  of  three  to  six  cells.  It  is  fre- 
quently found  in  small  bunches  in  the  sputum,  tissues,  etc.  It  rarely 
occurs  in  branching  form  and  with  club-shaped  ends. 

Motility. — Is  not  motile. 

Sporulation. — A  number  of  bright  bodies  are  frequently  seen  in  the 
cell,  but  cannot  bz  considered  true  spores.  The  bacillus  is  resistant  to 
heat,  dessication,  acids,  putrefaction,  etc.,  in  a  relatively  high  degree. 

Oxygen  Requirements. — It  is  a  facultative  anaerobe.  Requires  free 
access  of  oxygen  for  growth. 

Temperature.— Grows  best  at  37-39°  C.  Slight  variations  above  or  be- 
low this  temperature  will  stop  the  growth.  Will  not  grow  at  ordinary 
temperature. 

Behavior  to  Gelatin.— ^o  growth  at  ordinary  temperature.  Does  not 
peptonize  blood-serum. 

Infection. — Takes  place  ordinarily  along  the  respiratory  tract — Inha- 
I  lation  tuberculosis.  It  may  occur  through  wounds — Inoculation  tubercu- 
losis, also  through  food — Intestinal  tuberculosis.  The  bacilli  introduced 
into  the  intestines  may  localize  in  distant  parts  of  the  body. 


PRINCIPLES   OF   BACTERIOLOGICAL   TECHNIQUE. 


87 


METHOD    OF    STAINING    SPORES    OF    SPORE-BEARING    BACILLI. 

The  spores  when  free,  or  when  fully  formed  within  the  bacilli, 
are  very  difficult  to  stain,  but  by  heating  the  cover-glass  specimen 
five  or  six  times  with  carbol-fuchsin  or  gentian-violet,  they  will 
take  the  stain.  The  rods  will  decolorize  in  one  minute  in  a  3  per 
cent,  solution  of  HCL  alcohol,  and  after  washing  they  may  be 
stained  with  methyl ene-blue,  in  contrast  to  the  spores  if  fuchsin 
was  used,  or  if  the  spores  were  stained  with  violet  the  rods  may 
be  stained  with  Bismarck-brown. 


Tubercle  Baci 


Plate   17     Tubercle    Bacilli 

Photomicrograph  from  a  Coverglass  Specimen  obtained  from  sputum.     Mag.  X  1,000. 


*THE  DEMONSTRATION  OF  THE  FLAGELLA  OF  MOTILE  BACTERIA  AND 
A  SIMPLE   METHOD  OF   MAKING   PHOTOMICROGRAPHS. 

Methods  Worked  Out  by  the  Author. 

Motile  bacteria  should  be  represented  in  illustrations  just  as 
they  are  naturally.  The  photomicrographs  usually  displayed  in 
works  on  bacteriology  do  not  as  a  rule  represent  motile  bacteria 
as  they  should  be.  I,  therefore,  took  up  the  study  of  staining  these 
organisms  and  endeavored  to  discover  a  method  which  would  give 
good  results  with  all  kinds  of  bacteria  and  I  made  a  comparative 
study. 

I  have  always  obtained  the  best  results  with  all  species  of  bac- 
teria, excepting  the  anaerobic,  by  streaking  the  surface  of  2  per 
cent,  agar  in  Petri  dishes,  and  the  streaked  culture  should  always 


*From  my  address  delivered  before  the  Society  of  American  Bacteriologists, 
at  Philadelphia,  Dec.  27,  1904. 


88  CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 

be  made  from  the  young  growth  in  bouillon  and  never  from  an  agar 
or  gelatin  transfer.  I  usually  inoculate  a  tube  of  bouillon  the  night 
before  and  streak  the  surface  of  the  agar  early  on  the  following 
morning  and  then  place  the  dishes  in  optimum  temperature,  so  that 
I  may  get  the  most  rapid  growth  possible.  I  find  that  2  per  cent, 
agar  is  preferable  to  that  of  less  per  cent.,  because  the  bacteria 
as  a  rule  do  not  collect  much  debris  from  the  culture  media.  Bac- 
teria differ  widely  in  the  number  and  character  of  their  flagella. 
Some  are  peritrichous,  having  large  numbers  growing  out  from 
all  parts  of  the  cell;  some  are  lophotrichous,  having  a  bunch  of 


# 


■  it  ,« 


/ 


I       # 


Plate  18     Typhoid  Bacilli,   Flagellated 
Magnified  1,000  diameters. 

flagella  at  one  end;  some  are  amphitrichous,  having  a  flagellum 
at  either  end;  some  are  monotrichous,  having  a  single  terminal 
or  polar  flagellum.  The  flagella  of  different  organisms  vary  in  char- 
acter; some  are  extremely  fine,  so  delicate  that  they  stain  with 
difficulty;  some  are  long  and  wavy;  others  are  short  and  may  be 
almost  straight.  The  anaerobic  bacteria  possess  flagella  which  are 
extremely  curly,  and  it  is  possible  to  determine  from  the  character 
j'of  its  flagella  whether  an  organism  is  an  anaerobe  or  an  aerobe. 
'Many  motile  bacteria  produce  spiral  bodies  which  are  termed  "Giant 
Whips"  by  Novy;  some  of  these  will  reach  loo/x  in  length. 

I  found  that  the  methods  for  flagella  staining  described  by  the 
old  authors  had  to  be  modified  considerably  in  order  to  get  good 
results.  By  constant  practice  and  very  hard  work,  often  prolonged 
into  the  small  hours  of  the  morning,  I  finally  succeeded  in  my  ef- 


PRINCIPLES   OF   BACTERIOLOGICAL   TECHNIQUE.  89 

forts.  I  found  there  were  six  general  classes  of  bacteria,  each  dif- 
ferent from  the  other,  in  its  manner  of  growth,  making  it  neces- 
sary to  treat  each  class  in  a  different  manner.  I  divided  the  motile 
bacteria  into  six  classes  for  staining  purposes : 

FIRST — bacilli  which  grow  like  the  streaked  culture  of  the 
Typhoid,  such  as  Typhoid  and  Colon. 

SECOND — bacilli  which  produce  wrinkled  or  folded 
growths,  such  as  Mesentericus  fuscus. 

THIRD — bacilli  which  send  out  a  thin,  almost  transparent 
growth  over  the  surface  of  the  agar,  such  as  Bacillus  Subtilis  and 
Bacillus  Megatherium. 


^, 


V 


"^  m 

"'■'^^^r-. 


^ 


/ 


^'- 


^^m 


Plate  19     Bacillus  Mesentericus  Fuscus,   Flagellated 

Magnified  1,500  diameters. 

FOURTH — bacilli  which  produce  slime,  such  as  Bacillus  Vul- 
gatus  and  Bacillus  Viscosus, 

FIFTH — bacilli  which  produce  pigments,  such  as  Bacillus 
Prodigiosus  and  Bacillus  Cyanogenus. 

SIXTH — anaerobic  bacteria,  such  as  Bacillus  Tetanus,  Oede- 
ma and  Symptomatic  Anthrax,  etc. 


90  CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 

MANNER   01^   MAKING   SUSPENSIONS   IN   WATER. 

(i)  Bacteria  resembling  Typhoid  streak  cultures  have  very 
young  and  actively  motile  bacteria  on  the  periphery  of  the  growth. 
From  this  the  material  is  taken  and  transferred  to  a  large  drop  or 
two  of  distilled  water  which  has  previously  been  boiled.  The  plati- 
num loop  should  be  made  from  very  fine  platinum  wire,  only  about 
half  the  size  of  the  loop  used  for  general  purposes.  This  fine  loop 
will  gather  sufficient  material  without  taking  up  any  of  the  agar. 
The  material  usually  clings  tenaciously  to  the  loop,  but  may  be 
liberated  by  the  aid  of  another  platinum  wire,  if  care  is  exercised. 
The  bacteria  are  then  allowed  to  disseminate  spontaneously 
throughout  the  drop  of  water,  so  that  the  finest  specimens  will 
swim  to  the  outer  edges  from  which  the  cover-glass  preparation 
is  made.  Bacteria  which  have  few  flagella  and  those  whose  flagella 
have  been  broken  will  remain  near  the  center. 

(2)  Preparations  made  from  bacteria  which  produce  wrink- 
led or  folded  growth  are  made  before  the  wrinkled  growth  is 
formed.  In  order  to  get  a  good  preparation  from  this  group  of 
bacteria  the  agar  should  be  streaked  in  the  morning  and  then  care- 
fully watched  for  the  first  appearance  of  growth  and  from  this  a 
satisfactory  preparation  can  be  made. 

(3)  The  thin,  transparent,  spreading  growth  is  one  of  the 
best  for  demonstrating  flagella.  This  growth  is  almost  invisible 
and  is  composed  of  very  young  and  actively  motile  bacteria.  In  or- 
der to  get  a  good  preparation  from  this  a  curved  platinum  wire 
is  used  to  gently  collect  the  bacteria  en  masse  and  then  the  small 
loop  is  employed  to  make  transfers  to  the  distilled  water. 

(4)  The  slime-producing  bacteria  are  very  difficult  for  the 
demonstration  of  flagella.  The  slime  collects  between  the  flagella 
and  the  mordant  fixes  the  slime  as  well  as  the  flagella,  so  that  the 
stain  completely  covers  the  delicate  organs  of  locomotion.  I  found 
that  this  slime  could  be  precipitated  by  shaking  a  water  suspension 
with  chloroform.  A  very  young  growth  of  the  organism  is  used 
and  transfers  are  made  to  about  i  c.c.  of  distilled  water  in  the  test 
tube  until  the  water  is  made  very  cloudy.  The  slime  increases  the 
cloudiness  and  this  is  necessary  in  order  to  have  a  sufficient  number 
of  bacteria  to  make  a  fine  preparation.  This  cloudy  suspension  is 
then  shaken  with  chloroform,  which  seems  to  cut  away  the  slime 
from  between  the  flagella ;  then  the  cover-glass  preparation  is  made 
from  the  water  above  the  chloroform. 

(5)  Bacteria  which  produce  pigments  soluble  in  chloroform 
are  treated  in  the  same  manner.  Those  whose  pigments  are  soluble 
in  water  and  not  in  chloroform  are  more  difficult  to  stain.  I  usually 
hold  the  cover-glass  under  the  tap  after  fixing  the  preparation  in 


PRINCIPLES   OF   BACTERIOLOGICAL   TECHNIQUE. 


91 


r  I 


\ 


^. 


Plate  20     Bacillus  Subtilis,   Flagellated 
Magnified  1,000  diameters. 


1.     ^-^ 


Plate  21      Bacillus  Mesentericus  Vulgatas,   Flagellated 

Magnified  1.200  diameters. 


PRINCIPLES    OF   BACTERIOLOGICAL.   TECHNIQUE.  93 

the  flame  previous  to  adding  the  mordant.     In  this  way  much  of 
the  sohible  pigment  is  removed. 

(6)  Good  suspensions  of  anaerobic  bacteria  are  the  most  dif- 
ficult of  ah  to  obtain.  Bacteria  which  are  imbedded  in  stab  cul- 
tures do  not  make  good  preparations,  because  the  agar  and  debris 
cling  tenaciously  to  the  flagella.  It  is  extremely  difficult  to  get 
a  good  surface  growth  of  obligative  anaerobes,  because  it  usually 
requires  two  or  three  drops  of  a  young  bouillon  culture  for  surface 
inoculation  and  when  the  growth  appears  the  surface  is  covered 
with  the  old,  partially  dissolved  cells  and  free  spores.  Still,  some 
very  fine  preparations  can  be  made  from  the  surface  of  the  culture. 
The  best  results  are  obtained  as  follows :  The  medium  is  2  per 
cent,  glucose  agar  in  slants  and  the  inoculation  is  made  back  of  the 
slant  between  the  agar  and  the  wall  of  the  tube.  I  slide  the  needle 
down  back  of  the  slant  and  let  it  fall  forward ;  I  introduce  two  or 
three  drops  of  a  young  bouillon  culture  and  then  replace  the  agar. 
By  excluding  oxygen  and  maintaining  a  blood  temperature  for 
thirty-six  hours,  a  fine  growth  of  bacteria  usually  appears  between 
the  agar  and  the  wall  of  the  tube  and  beautiful  preparations  can  be 
made  from  this.  Many  rods  containing  spores  still  retain  a  full 
equipment  of  flagella. 


CLKANING  THE  COVER-GLASSES. 

I  prefer  the  No.  i  round  cover-glass,  which  when  new  are  cov- 
ered with  a  thick,  greasy  substance  quite  difficult  to  remove.  Cover- 
glasses  used  for  the  demonstration  of  flagella  must  be  absolutely 
clean,  and  this  is  a  most  important  feature.  For  removing  the 
grease  they  are  covered  with  suphuric  acid  and  allowed  to  stand  for 
one  day.  The  sulphuric  acid  is  poured  off  and  they  are  then  cov- 
ered with  bichromate  of  potassium  and  allowed  to  remain  in  this  for 
several  hours.  This  acid  is  then  poured  off  and  the  cover-glasses 
are  washed  with  distilled  water  and  transferred  to  a  jar  containing 
absolute  alcohol,  where  they  remain  until  ready  for  use.  A  single 
cover-glass  is  removed  with  clean  forceps  from  the  alcohol,  trans- 
ferred to  a  piece  of  clean,  well-washed  linen  and  dried  without 
touching  it  with  the  fingers.  The  cover-glass  is  then  taken  in  the 
forceps  and  passed  several  times  through  the  Bunsen  flame,  so 
that  every  particle  of  fat  or  grease  is  removed,  and  it  must  appear 
clear  and  free  from  blemishes.  Many  cover-glasses  are  lost  after 
heating  in  the  flame,  particularly  if  there  are  an}^  currents  of  cold 
air  through  the  room,  but  since  the  perfect  condition  of  the  cover- 
glass  is  so  important  the  loss  of  two  or  three  is  immaterial. 


94  CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 


Bacillus  Oedematis  Maligni,  No.  2,  Novy  (1893) 

Origin. — Obtained  from  guinea-pigs  which  had  been  inoculated  with 
milk  nuclein  obtained  from  casein  by  digestion  with  artificial  gastric  juice. 

Form. — In  the  animal  body  it  is  usually  found  m  single  rods,  four  to 
five  times  as  long  as  wide ;  also  occurs  in  short  threads.  On  artificial 
media  the  rods  are  straight  or  bent;  peculiarly  twisted  threads  are  some- 
times formed.  The  contents  are  frequently  granular,  showing  a  bright 
body  at  one  end. 

Motility. — A  slight,  swaying  motion,  which  is  not  always  present. 
Possesses  lateral  flagella,  and  gives  rise  to  giant  whips  40  to  72  microns 
long  in  pure  cultures  as  well  as  in  the  animal. 

Sporulation. — Has  not  been  observed. 

Anilin  Dyes. — Stain  readily.     Gram's  method  may  be  used. 

Growth. — Depends  upon  vitality.  Grows  rapidly  when  taken  from  an 
animal. 

Plates. — On  glucose  agar  at  ^7°  good  colonies  will  develop  in  two 
or  three  days ;  these  have  irregular,  fibrillated  border,  and  frequently  de- 
velop gas  bubbles.     Giant  whips  are  sometimes  found. 

Stab  Culture. — Grows  only  in  the  lower  part  of  the  tube.  In  glucose 
agar  properly  alkaline,  a  distinctly  visible  growth  develops  along  the 
line  of  inoculation ;  gas  is  produced  which  soon  tears  apart  the  agar.  The 
cultures  soon  die  out. 

Streak  Culture. — Grows  on  glucose  agar  only  when  oxygen  is  com- 
pletely excluded ;  grows  in  the  form  of  a  white  film,  spreading  over  the 
surface.     Involution  forms  develop  on  acid  agar. 

Bouillon. — A  fine  growth  is  developed  which  settles  to  the  bottom  as 
a  loose,  flocculent  sediment  in  twenty-four  hours ;  the  liquid  above  be- 
coming clear. 

Glucose  Gelatin  colored  with  litmus. — Liquefies  and  produces  acid. 
The  litmus  is  reduced  and  turned  red. 

Oxygen  Requirements. — It  is  an  obligative  anaerobe.  Will  grow  in 
vacuum  hydrogen,  nitrogen,  carbonic  acid  and  illuminating  gas. 

Temperature. — Does  not  grow  below  25°  C.  Grows  best  at  about  39° 
Will   withstand   freezing   for  twenty-four  hours. 

Behavior  to  Gelatin. — Liquefies. 

Aerogenesis. — Produces  gases  in  alkaline  media.  Forms  volatile  acids, 
as  butyric  acids,  etc.,  in  artificial  cultures  and  also  in  the  body  of  rabbits. 

Attenuation. — Cultures  lose  their  virulence  when  exposed  to  light  or 
left  in  hydrogen.  Can  be  kept  in  the  dark  or  by  passing  through  animals. 
Lost  virulence  may  be  restored  by  inoculation  with  a  mixed  culture  con- 
taining Proteus  vulgaris. 

Immunity. — Is  not  produced  by  non-fatal  inoculation,  or  by  old 
weakened  cultures,  or  by  the  serous   exudate  of  the  pleural  cavity. 

Pathogenesis. — Subcutaneous  injection  of  ^/4  c.  c.  of  hydrogen  bouillon 
cultures  wall  kill  guinea-pigs,  white  rats,  white  mice,  rabbits  or  doves, 
in  twelve  to  twenty-four  hours.  Marked  subcutaneous  edema  are  present. 
Serous  exudates  in  thoracic  and  abdominal  cavities.  Cover-glass  prepara- 
tions made  from  subcutaneous  tissue  or  serous  surfaces  usually  show 
very  large  numbers  of  bacilli;  giant  whips  are  also  frequently  present,  be- 
ing visible  as  colorless   spirals. 

Diagnosis. — It  is  readily  distinguished  from  symptomatic  anthrax  and 
malignant   edema   by   morphological    characteristics. 


PRINCIPLES   OF   BACTERIOLOGICAL   TECHNIQUE. 


^^ 


Plate  22     Bacillus  Tetanus,   Flagellated 

Magnified  1,200  diameters. 


Plate  23      Bacillu>  ot   Maliunant  Oedema 

Magnified  1,500  diameters. 


principles  of  bacteriological.  technique.  97 

pre:paration  of  the:  staining  agents. 

The  fixing  agent  is  mordant  and  the  stain  is  carbol  gentian 
violet  or  preferably  carbol  fuchsine. 

THE  MORDANT. 

2  grams  dessicated  tannic  acid. 

5  grams  cold  saturated  solution  ferrous  sulphate  (aqueous). 

15  c.c.  distilled  water. 

I  c.c.  saturated  alcoholic  solution  of  fuchsine. 

The  tannic  acid  is  dissolved  in  the  water  first,  by  the  applica- 
tion, of  gentle  heat;  then  the  ferrous  sulphate  and  then  the  alco- 
holic solution  of  fuchsine  are  added. 

To  these  ingredients,  I  have  always  found  it  advisable  to  add 
a  certain  amount  of  sodium  hydroxid,  a  i  per  cent,  solution,  varying 
from  ^  to  I  c.c.  The  best  grade  of  filter  paper  is  used  for  filter- 
ing the  mordant,  and  there  should  be  left  a  heavy  precipitate.  Af- 
ter filtering,  the  color  of  this  mordant  should  be  of  a  reddish-brown 
hue,  not  clear,  but  somewhat  cloudy,  and  this  mordant  must  be 
used  within  five  hours  after  it  is  made.  After  that  time,  it  loses  its 
staining  power.  This  is  indicated  by  its  gradual  clarification  and 
darkened  color.  It  gives  the  best  results  when  strictly  fresh,  and 
accomplishes  its  work  in  a  much  shorter  time,  so  that  very  little  if 
any  heating  is  required  when  it  is  placed  on  the  cover-glass  prep- 
aration. 

CARBOL   FUCHSINE. 

Take  about  one  gram  of  granulated  fuchsine  (not  the  acid 
fuchsine),  put  it  in  a  bottle,  and  pour  over  it  about  25  c.c.  of  warm 
absolute  alcohol.  Shake  vigorously,  and  let  it  stand  for  several 
hours  before  using.  The  carbol  fuchsine  is  made  by  diluting  the 
saturated  alcoholic  solution  four  or  five  times  with  a  5  per  cent, 
solution  of  carbolic  acid.  Carbol  fuchsine  should  be  freshly  made, 
heated  and  filtered  before  using. 

Every  organism  differs  from  other  organisms  in  its  manner 
of  absorbing  the  stain,  so  that  some  experimental  work  is  necessary 
to  determine  just  how  the  stain  should  be  applied.  In  a  general 
way  we  proceed  as  follows :  A  small  loop  full  of  the  clouded  wa- 
ter, obtained  as  described  in  the  first  part  of  this  article,  is  trans- 
ferred to  the  cover-glass  and  gently  spread  over  as  large  a  sur- 
face as  possible.  Care  must  be  exercised  in  spreading  the  drop.  I 
usually  carry  the  drop  around  the  surface  without  touching  the 
glass  with  the  loop.  In  this  way  the  surface  is  moistened,  and  the 
loop  does  not  tear  ofif  the  flagella.  A  confluent  spread  does  not 
give  as  good  satisfaction  as  a  streak  spread  with  a  small  space  be- 


;  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

Bacillus  Anthracis  Symptomatici,Feser  and  Bollinger ( 18  78) 

SYMPTOMATIC    ANTHRAX^    BLACK    LEG^    QUARTER    EVIL;    CHARBON 
SYMPTOM ATIQUE    (FR.)  ;    RAUSCHBRAND    (GERM.) 

Origin. — Found  in  the  subcutaneous  tissue,  muscles,  serous  exudate, 
etc.,  of  symptomatic  anthrax. 

Form. — Rather  large,  narrow  rods,  having  rounded  ends ;  almost 
alw^ays  single,  but  sometimes  are  found  in  pairs.  About  three  times  as 
long  as  wide.  Involution  forms  are  seen  in  old  cultures — swollen  at  the 
ends  or  in  the  middle. 

Motility. — Actively  motile,  having  lateral  flagella;  giant  whips  are 
often  found.     Spore-bearing  rods  lose  their  motion  eventually. 

Sporulaiion. — Spores  develop  near  one  end,  which  is  enlarged;  they 
are  bright  and  oval  in  form ;   are  not  formed  in  body  until  after  death. 

Anilin  Dyes. — Stain  readily.  Will  stain  by  Gram's  method  if  a  strong 
dye  acts  for  some  time.     Spores  may  be  readily  double  stained. 

Growth. — Rapid ;  best  in  acid  or  alkaline  glucose  media ;  attended  with 
strong  butyric  acid  odor.  Will  not  grow  except  under  anaerobic  condi- 
tions. 

Plates. — On  gelatin,  irregular  masses  are  formed  surrounded  by  dense 
whorl  of  threads.  Gelatin  is  liquefied.  On  agar,  the  colonies  usually  ap- 
pear as  dense  masses  of  threads ;  they  vary,  however. 

Stab  Culture. — In  glucose  gelatin,  growth  takes  place  in  the  lower 
part  of  the  tube ;  gas  is  produced ;  contents  liquefied.  In  glucose  agar, 
growth  is  energetic  and  gas  is  produced,  the  contents  of  the  tube  being 
torn  into   several  parts.     Giant  whips  common    (Novy). 

Streak  Culture. — On  glucose  agar  in  hydrogen,  a  whitish,  spreading 
film  is  formed.     On  blood  serum,  growth  is  good;  giant  whips   (LoefHer). 

Bouillon. — Is  clouded;  gas  bubbles  accumulate  on  the  surface;  the 
growth  settles  to  the  bottom  after  several  days,  forming  a  compact,  ad- 
herent sediment ;  liquid  above  remains  cloudy  for  several  days. 

Glucose  Gelatin,  Colored  with  Litmus. — Under  ordinary  circumstances, 
growth  develops  in  incubator.  The  litmus  is  reduced,  then  colored  a 
wine-red,  showing  formation  of  acid.  Heavy,  flocculent  sediment  is  de- 
posited on  the  bottom. 

Milk. — Coagulates  casein  rapidly;  does  not  invert  starch.  Grows  on 
potato. 

Oxygen  Requirements. — It  is  an  obligative  anaerobe.  Will  grow  in 
hydrogen,  vacuum,  carbonic  acid,  etc.  Grows  in  glucose  litmus  gelatin  in 
presence  of  air. 

Temperature. — Grows  best  at  37-38°  C.  Will  grow  slowly  at  room 
temperature. 

Behavior  to  Gelatin. — Liquefies. 

Aerogenesis. — Produces  gas  with  disagreeable  odor ;  gas  is  inflam- 
mable, consisting  of  marsh-gas,  hydrogen,  etc. 

Attentuation. — Bouillon  cultures  lose  their  virulence  soon  but  retain 
vitality.  Attenuation  occurs  at  42-43°.  Dry  spore-bearing  material  be- 
comes attenuated  when  heated  to  80°  or  100°.  Virulence  may  be  restored 
by  inoculating  animals,  at  the  same  time  injecting  some  lactic  acid.  Vir- 
ulence is  maintained  in  solid  media. 

Immunity. — Alay  be  obtained  by  inoculating  small  amounts  of  viru- 
lent germ;  by  intravenous  injections;  by  injection  of  heated  cultures,  80* 
or   100° ;   in  active  old  cultures ;   filtered   cultures. 

Pathogenesis. — Young  cattle,  sheep,  goats,  guinea-pigs  and  mice  are 
highly  susceptible.  The  horse,  ass  and  white  rat  are  less  susceptible. 
Hogs,  dogs,  rabbits,  ordinary  rats,  doves,  ducks  and  chickens  are  almost 
immune.  Death  is  produced  in  twentj^-four  to  forty-eight  hours  in 
guinea-pigs  by  subcutaneous  injection.  Extensive  subcutaneous  bloody 
edema  is  present.     Gas  is  present.     The  muscles  are  dark  and  infiltrated. 

Infection. — Occurs  naturally  by  inoculation  through  deep  wounds ; 
very  rarely  through  food.     Poisoned  arrows   used  in  fishing  in   Norway. 

Diagnosis. — It  is  especially  a  disease  of  cattle,  and  not  of  man.  It 
is  difficult  to  distinguish  the  bacillus  from  malignant  edema  bacillus.  In 
oculation  of  the  rabbit  is  negative,  threads  are  absent;  tendency  to  in- 
volutions. It  is  distinguished  from  anthrax  bacillus  by  form,  motility,, 
by  its  distribution  in  the  body  and  by  cultural  properties. 


PRINCIPLES    OF   BACTERIOLOGICAL   TECHNIQUE. 


99 


Plate  24     Bacillus  of  Symptotiiatic  Anthrax,  Flagellated 

Magnified  1,200  diameters. 


Plate  25     Asiatic  Cholera,   Flagellated 

Magnified  2,000  diameters. 


PRINCIPLES   OF   BACTERIOLOGICAL   TECHNIQUE.  IQI 

tween  each  streak.  The  finest  specimens  for  photomicrography  are 
obtained  from  the  periphery  of  the  streaks.  The  spreading  must 
be  done  rapidly  because  evaporation  takes  place  very  soon.  After 
evaporation  takes  place,  there  should  appear  very  thin  films  along 
the  track  of  the  loop.  The  preparation  must  be  fixed  in  the  flame 
80^ that  the  bacteria  will  not  wash  off  during  the  staining,  but  the 
fixing  must  not  be  accompanied  by  too  much  heating,  because  the 
delicate  organs  of  locomotion  are  easily  burned  off.  The  Bunsen 
flame  should  be  about  one  inch  high;  the  glass  held  by  the  forceps, 
preparation  side  up,  is  passed  down  on  to  the  flame  just  once  and 
instantly  removed.  The  cover-glass  is  then  ready  for  the  mordant, 
which  is  poured  on,  just  enough  to  cover  the  surface  without  flow- 
ing over  the  edges.  I  find  that  the  Cornet  forceps  are  best  suited 
for  staining  purposes,  and  if  the  cover-glass  be  held  just  a  short 
distance  within  the  edge,  the  mordant  or  stain  will  not  run  off. 
It  usually  happens  that  we  are  unsuccessful  in  demonstrating  fla- 
gella,  if  the  mordant  runs  off,  or  goes  on  the  under  side  of  the  glass. 
During  the  steaming  of  the  mordant,  it  is  advisable  to  keep  up  a 
rotary  motion  in  order  to  avoid  too  much  precipitation.  When  the 
mordant  is  fresh,  it  requires  only  about  one-half  to  one  minute  to 
get  sufficient  staining.  The  mordant  is  completely  washed  off  un- 
der the  tap,  and  this  is  done  pretty  thoroughly;  a  small  quantity  of 
absolute  alcohol  is  poured  onto  the  surafce,  and  this  is  instantly 
washed  off.  The  alcohol  removes  a  great  deal  of  the  precipitation 
whiich  is  found  in  cover-glass  preparations,  but  considerable  care 
should  be  taken  to  wash  it  off  quickly  and  thoroughly,  because  it 
will  remove  the  germs  and  flagella,  if  it  is  allowed  to  act  only  for 
a  short  time.  If  the  alcohol  is  thoroughly  washed  off,  the  water  is 
removed  by  holding  the  glass  edgeways  to  a  piece  of  filter  paper. 
If  the  filter  paper  is  not  clean,  considerable  dust  and  fiber  will 
be  carried  up  on  to  the  cover-glass,  and  if  there  is  any  danger  of 
this,  it  is  better  to  finally  wash  the  cover-glass  off  with  the  dis- 
tilled water  and  shake  off  the  drops  which  cling  to  the  glass.  Then 
cover  the  surface  with  a  carbol  fuchsine  or  carbol  gentian  violet. 
I  find  in  nearly  all  cases,  that  fuchsine  is  better  than  violet,  and 
gives  less  precipitation,  but  in  some  cases  the  gentian  violet  brings 
out  the  flagella  more  prominently.  This  must  be  fresh,  however, 
and  thoroughly  washed  off  after  staining.  We  allow  the  fuchsine 
to  stand  on  the  cover-glass  for  about  one-half  minute,  being  heated 
just  sufficiently  for  a  thin  vapor  to  be  visible.  We  then  heat  it  so 
that  steam  is  given  off  quite  freely,  but  never  until  ebullition  takes 
place.  Care  must  be  used  when  heating  the  stain,  because  it  is  not 
unusual  to  find  that  there  is  entirely  too  much  precipitation,  and 
the  flagella  are  burned  off.  It  rarely  happens  that  we  get  a  cover- 
glass  which  will  be  stained  well  all  over.  Usually  we  get  only  cer- 
tain sections  where  the  flagella  stand  out  prominently,  and  the  field 


102  CANNING    AND    PRESERVING    OF    FOOD    PRODUCTS. 

is  free  from  precipitation.  Views  sufficiently  attractive  for  photo- 
micrographing  are  rare.  While  the  staining  may  be  perfect,  there 
will  be  some  defects  in  the  germs.  Some  may  have  lost  part  of 
their  liagella,  or  there  may  be  too  much  precipitation  in  the  field, 
or  the  germs  may  be  too  close  together  or  too  scattered,  and  the 
ideal  views  for  photomicrography  are  few,  and  it  is  sometimes  nec- 
essary to  stain  up  several  cover-glasses,  before  we  get  a  fine  view. 
During  the  staining  with  the  mordant  and  dye,  a  thin  film  is  form- 
ed all  over  the  glass.  This  must  not  be  broken  up  by  the  applica- 
tion of  too  much  alcohol,  if  a  clear  field  is  desired. 

Some  writers  advocate  the  idea  of  examining  the  cover-glass 
preparations  on  the  slide  with  a  drop  of  water  under  the  cover- 
glass,  before  finally  clearing  and  mounting  the  specimen.  I  have 
been  unfortunate  in  this  procedure,  and  on  several  occasions  have 
lost  some  beautiful  specimens  on  attempting  to  float  off  the  cover- 
glass  with  water,  after  examination.  It  frequently  happens  that  the 
germs  will  stick  to  the  slide  and  pull  off,  leaving  graves  surrounded 
by  beautiful  bunches  of  flagella,  so  I  make  it  a  rule  to  mount  my 
cover-glass  in  xylol-balsam,  as  soon  as  I  have  finished  staining.  I 
do  this  as  follows : 

I  select  very  thin  slides,  pieces  of  glass  about  3  inches  long  and 
I  inch  wide,  perfectly  clear,  and  having  no  blisters.  Having  thor- 
oughly cleaned  the  slide,  I  heat  it  over  the  flame  to  drive  off  mois- 
ture, and  place  in  the  center  a  small  drop  of  xylol-balsam  (which  is 
Canada  balsam  dissolved  in  xylol,  and  comes  in  collapsible  tubes). 
After  thoroughly  dr3dng  the  water  from  the  cover-glass  after  stain- 
ing, I  pour  pure  xylol  all  over  the  surface,  and  immediately  touch 
the  edge  to  clean  filter  paper,  and  then  drive  off  the  xylol  with 
heat.  It  is  absolutely  necessary  to  have  the  cover-glass  free  from 
moisture  before  applying  x3dol.  (X3dol  is  a  refined  benzine). 
Otherwise,  a  hazy  appearance  will  be  imparted  to  the  preparation, 
and  this  spoils  it  for  microscopical  purposes.  After  clearing  with 
xylol  and  drying,  the  drop  of  balsam  is  heated  gently  and  the  cover- 
glass,  preparation  side  down,  is  pressed  on  to  the  slide  so  that  the 
balsam  is  spread  out  in  a  thin  layer  between  the  two  pieces  of  glass, 
and  the  preparation  is,  of  course,  thus  protected  from  injury.  The 
method  for  the  demonstration  of  the  flagella  of  different  organisms 
varies,  as  we  have  said.  The  differences  which  I  have  noticed  have 
been  in  the  length  of  time  allowed  for  staining  with  the  mordant, 
and  the  f uchsine ;  also  the  amount  of  i  per  cent,  sodium  hydroxid. 
Great  success  is  achieved  only  by  careful  and  patient  study  of  each 
organism.  It  is  not  a  difficult  matter  to  demonstrate  the  flagella 
of  most  motile  organisms,  but  to  get  beautiful  preparations  is  a 
study,  and  requires  great  care  in  every  step  of  the  work. 


PRINCIPLES   OP   BACTERIOLOGICAIi   TECHNIQUE.  103 

SUMMARY. 

Culture  to  be  made  on  2  per  cent,  agar  from  young  growth 
in  bouillon. 

Suspensions  in  water  to  be  made  according  to  nature  of  or- 
ganism. 

Cover-glasses  to  be  absolutely  clean. 

Mordant  to  be  used  only  when  fresh. 

Dye  to  be  made  fresh  and  used  while  warm. 

Spread  on  cover-glass  not  to  be  confluent. 

Fixing  to  be  done  without  injury  to  flagella. 

Staining  to  be  done  without  overheating. 

Washing  with  alcohol  and  water  without  breaking  the  film. 

Clearing  with  xylol  after  thorough  drying. 

Mounting  in  xylol-balsam  without  previous  examination. 


A  SIMPI.E  METHOD  OF  MAKING  PHOTOMICROGRAPHS. 

A  large,  cumbersome  apparatus  is  unnecessary.  The  camera 
is  about  twice  as  long  as  the  ordinary  4x5  camera,  and  the  photo- 
micrographs are  taken  with  the  camera  in  a  horizontal  position. 
It  must  be  a  steady  apparatus  and  the  microscope  stand  should  be 
substantial  and  with  the  cone  fine  adjustment.  Much  depends  upon 
the  objective.  In  order  to  get  negatives  showing  a  flat  field  with 
clean  definition  I  have  used  nearly  all  kinds  of  objectives,  but  have 
found  none  equal  to  the  1-12  oil  immersion  objective  and  No.  6 
compensating  eye-piece  made  by  the  Spencer  Lens  Co.  The  best 
plates  are  the  isochromatic  or  orthochromatic  swift  plates,  which 
are  correct  for  colors.  I  have  found  the  acetylene  radiant,  prefer- 
able to  gas,  oil  or  electric  light.  It  is  slower  than  electric  light,  but 
brings  out  all  details  with  wonderful  nicety.  The  only  screen  I 
ever  use  is  green  glass.  Printing  from  the  negatives  on  glossy 
Velox  brings  out  the  best  detail.  The  glossy  Velox  is  then  ferro- 
plated,  which  makes  a  beautiful  photograph. 


104  CANNING  AND  PRESERVING  OP  FOOD  PRODUCTS. 

CHAPTER  IV. 

Decomposition  Caused  by  Micro-Organisms 

Decomposition  Caused  by  Micro-organisms.  Fermentation  The- 
ories. Vacuum  Theory.  AlcohoHc  Fermentation.  Acetic 
Fermentation.  Butyric  Fermentation.  Lactic  Fermentation. 
Putrefaction.    Reprocessing  Leaks  a  Dangerous  Proceeding. 


The  word  fermentation  is  derived  from  the  Latin  word  fermeo, 
meaning  to  boil.  The  appearance  of  Hquids  in  agitation  due  to  the 
vital  action  of  micro-organisms  no  doubt  gave  rise  to  the  word. 

The  word  fermentation  as  commonly  used,  implies  more  than 
the  processes  of  decomposition  accomplished  by  bacteria,  molds  and 
yeasts.  Micro-decomposition  is  perhaps  a  better  term,  since  it  ap- 
plies directly  to  the  breaking  down  processes  accomplished  by  micro- 
organisms and  their  enzymes  (products  formed)  only,  and  does  not 
take  in  the  chemical  changes  induced  by  chemicals,  rennets  and 
animal  secretions.  The  term  embraces  also  the  different  processes 
of  putrefaction,  which  are  separated  by  some  authors,  but  it  seems 
to  me  that  they  should  be  considered  under  one  head. 

FBRMBNTATION  was  the  term  that  was  applied  to  these 
processes  by  the  early  investigators,  and  the  history  of  their  labors 
and  deductions  is  interesting,  since  it  shows  us  the  difficulties  with 
which  they  were  beset  and  permits  us  to  see  the  rays  of  light  and 
truth  as  they  are  let  into  the  darkness  by  the  different  stars  in  the 
scientific  world  from  the  time  of  Leeuwenhoek  down  to  the  present. 

The  early  investigators,  a  few  excepted,  fell  victims  to  the 
false  theory  of  Spontaneous  Generation.  Needham  (in  1745) 
founded  a  demonstration  of  this  theory  on  his  failures  to  preserve 
meat  juices  by  boiling  in  flasks,  claiming  that  ''infusoria"  were 
spontaneously  created  from  the  juices  themselves. 

In  1765  Abbe  Spallanzani  took  the  opposite  stand,  claiming 
that  if  air,  which  had  been  exposed  to  fire,  were  admitted  to  flasks 
containing  meat  extracts,  the  "animalcules"  would  not  develop.  In 
1836  Franz  Schultz  conceived  the  idea  of  filling  the  flasks  with 
air  filtered  through  sulphuric  acid  and  potassium  hydroxid,  which 
gave  him  encouragement  as  an  opponent  of  the  spontaneous  theory. 
The  other  side  claimed  that  a  chemical  change  in  the  air  was  made 
bv  such  experiments  which  made  it  impossible  for  the  animalcules 
to  hatch   from  the  vital   principles  of  the   infusions.      They  also 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  105 

found  that  the  methods  referred  to  were  not  rehable  and  that  micro- 
organisms would  make  their  appearance  in  many  cases.  Thus  the 
study  of  fermentation  and  its  causes  began  to  occupy  the  attention 
of  investigators.  In  1862  Pasteur  pubhshed  his  researches  on  fer- 
mentation and  Von  Liebig  stiU  opposed  him  with  the  theory  of 
spontaneous  generation.  Then  Tyndall  came  forward  with  his  ab- 
solute proof  that  micro-organisms  did  not  develop  from  inorganic 
protoplasm  (elementary  compounds),  but  that  they  developed  only 
as  they  found  admittance  through  the  atmosphere  and  that  if  in- 
fiisions  were  sterilized  fermentation  could  not  possibly  take  place. 
By  this  intermittent  heat  process  he  sterilized  all  kinds  of  liquids 
and  solid  food  substances  and  gave  the  opposition  such  a  blow  that 
the  "spontaneous"  theory  fell. 

The  theory  is  only  unproved,  however,  since  all  must  admit  of 
a  beginning  of  all  life.  That  the  beginning  of  a  species  is  due  to 
a  creative  power  is  probably  the  best  w^ay  of  disposing  of  the  ques- 
tion; at  what  time  we  cannot  say;  whether  it  is  still  going  on  we 
cannot  say;  but  there  is  evidence  that  such  is  the  case. 

There  are  several  kinds  of  decomposition  which  cannot  be  as- 
cribed to  the  action  of  micro-organisms  which  the  word  fermenta- 
tion would  include.  There  is  a  spontaneous  decomposition  of  sugar 
in  vegetable  and  fruit  cells,  which  w-hen  kept  in  a  pure  and  un- 
contaminated  condition,  liberate  carbonic  acid  gas  COg,  and  form 
alcohol  in  appreciable  quantities.  This  is  no  doubt  due  to 
the  life  of  the  fruit  itself,  which  Ts  living  protoplasm,  and 
wlien  seeds  are  present,  vital  principles  are  therein  contained 
which  have  the  power  to  decompose  the  sugar  in  the  fruit  or  vege- 
table cells.  It  is  a  curious  fact  that  when  a  whole  tomato  is  heated 
in  a  flask  to  the  boiling  point,  after  a  lapse  of  time  it  will  be  found 
quite  devoid  of  sugar  so  far  as  taste  is  concerned.  Quite  a  liberal 
quantity  of  gas  will  be  liberated  also,  and  when  the  seeds  are  ex- 
amined carefully  the  gelatinous  envelope  will  be  found  perfect  as 
before  heating  and  the  seeds  are  capable  of  germinating  when 
planted.  The  decomposition  takes  place  without  the  vital  activity 
of  micro-organisms.  The  experiment  may  be  made  by  anyone  in- 
terested by  placing  a  perfectly  sound  ripe  tomato  in  a  thin  glass 
jar  and  melting  the  top  down  to  a  narrow  neck  by  means  of  a  blow 
pipe,  (the  skin  of  the  tomato  should  be  washed  off  with  a  solu- 
tion of  bi-chlord  of  mercury).  This  narrow  neck  may  be  stuffed 
with  sterilized  cotton  and  the  flask  held  over  the  flame  just  long 
enough  to  permit  steam  to  flow  freely  through  the  cotton.  A  bent 
tube  may  be  fastened  with  rubber  over  the  neck  of  the  flask  and 
the  end  submerged  in  a  dish  of  water.  To  measure  the  escaping 
carbon  dioxid,  a  bottle  with  water  is  inverted  over  the  end  of  the 
tube  under  water,  i  As  fast  as  the  gas  is  evolved  the  water  is  ex- 
pelled from  the  bottle,  but  the  process  is  slow. 


106 


CANNING    AND    PRESERVING    OF    POOD    PRODUCTS. 


I  have  investigated  a  number  of  cases  of  so-called  spring  bot- 
toms in  cans  of  fruit,  especially  California  fruits.  Cases  of  canned 
fruit  are  frequently  found  where  the  bottoms  of  the  cans  spring, 
showing  that  there  is  no  vacuum  in  them  and  quite  a  quantitjv^f 
gas7  sufficient  to  cause  the  bottom  to  spring  out  when  pressed  in 
by  the  hand. 


Fig.  29 


In  some  cases  I  have  found  wild  yeasts  to  be  the  cause^  but 
more  frequently  the  cans  are  quite  free  from  bacteria  or  fungi  of  all 
kinds.  This  led  me  to  the  conclusion  that  there  was  decomposi- 
tion going  on  from  a  different  cause,  and  after  experimenting  I 
found  in  some  cases,  after  a  few  months  that  the  cells  of  the  canned 
fruits  were  actually  losing  sugar  and  that  considerable  carbon  di- 
oxid  was  being  set  free.  After  applying  heat  sufficient  to  kill  the 
cell  life  of  such  fruit,  the  phenomenon  is  no  longer  ohsevved.~CanA 
ned  fruits  zv ill  therefore  undergo  spontaneous  decomposition  if  suf- 
ficient heat  is  not  employed  in  the  sterilizing  process  to  destroy  the 
life  of  the  cells.  The  fruit  flavor  suffers  to  some  extent  from  the 
extended  sterilization,  but  the  trouble  and  loss  is  avoided.  One 
other  fact  deserves  mention  in  this  connection  and  that  is  the  tem- 
perature which  develops  spring  bottoms.  If  the  cans  are  stored 
in  a  temperature  of  40°  to  50°  F.  and  opened  before  being  allowed 
to  reach  a  warmer  temperature,  even  the  underprocessed  fruits  will 
be  found  to  be  free  from  partial  decomposition.  It  usually  hap- 
pens that  the  trouble  is  experienced  after  the  cases  are  brought  out 
for  sale  in  the  early  summer,  just  before  the  fruit  season  opens. 
Wholesale  grocers  who  buy  heavily  in  the  fall  and  store  the  goods, 
usually  experience  some  trouble  when  the  cases  are  brought  out  in 
warmer  weather  for  the  trade. 

There  is  another  cause  of  decomposition,  and  that  is  the  influ- 
ence of  light  on  canned  goods,  particularly  foods  canned  in  glass. 
This  is  true  of  foods  containing  tartaric  acid,  glucose,  lactose  and 
maltose,  etc.,  especially  if  the  foods  are  faintly  alkaline  or  if  alkalies 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  107 

are  present  even  in  small  quantities.  The  action  of  sunlight  on  ex- 
posed solutions  containing  tartaric  acid  may  be  expressed  by  the 
following  chemical  equation : 

QHeOe  +  3O  =  2CH,02  +  2CO2  +  H^O. 

Tartaric  acid  +  Oxygen  =  Formic  acid  +  Carbon  dioxide  + 
Water. 

Glucose  and  lactose  have  been  found  on  exposure  to  sunlight 
in  hermetically  sealed  packages  to  break  down  and  form  alcohol  and 
carbon  dioxid,  or  just  the  same  fermentation  that  is  caused  directly 
by  the  yeast  plants  (Saccharomyces).  The  same  two  substances 
may  yield,  in  the  presence  of  lime,  lactic  acid  and  carbon  dioxid, 
or  a  fermentation  corresponding  to  that  produced  by  the  bacteria 
which  cause  the  souring  of  milk.  Thus  maltose  is  broken  up,  and 
yields  dextro-lactic  acid;  levulose  yields  levo-lactic  acid,  and  invert 
sugar  will  yield  an  inactive  acid,  when  polarized. 

A  word  of  advice  to  canners  of  food  products  in  glass  might 
he  opportune  in  this  connection.  Wrap  your  glass  goods  well,  and 
in^eadi  case  put  cards  requesting  the  retailer  not  to  remove  the 
paper  when  he  places  his  goods  on  the  shelf.  All  such  goods  should 
be  neatly  wrapped  and  have  labels  on  the  outside  sufficiently  at- 
tractive for  the  shelf.  Goods  unwrapped  for  show  windows  should 
be  sold  very  soon  on  account  of  the  danger  of  chemical  changes 
noted  above. 

The  word  fermentation  has  a  wide  meaning,  in  fact  it  is  a 
word  to  which  various  definitions  have  been  given  not  in  accord 
with  its  root  meaning,  and  it  is  made  to  embrace  all  such  transfor- 
mations and  decompositions  as  we  have  just  described,  so  we  return 
to  the  word  micro-decomposition  as  one  which  defines  the  changes 
jDToduced  by  fungi  directly. 

Bacteria  molds  and  yeasts  are  nutrient  food  substances  to  build 
up  cell  protoplasm,  and  this  is  followed,  or  there  goes  on  at  the 
same  time,  an  excretion  of  waste  materials  which  have  received  the 
names  of  enzymes  and  toxins.  There  are  formed  at  the  same  time 
various  acids  and  chemical  compounds  as  a  result  of  the  disturb- 
ances caused  by  the  utilization,  by  bacteria,  of  certain  elements  such 
as  carbon,  oxygen,  hydrogen  and  nitrogen,  which  are  torn  from  the 
molecules  containing  them,  thus  setting  free  other  atoms  which  unite 
to  form  those  products  of  decomposition.  To  make  this  clear  to 
the  reader  not  familiar  with  chemistry  it  may  be  explained  thus : 
A  molecule  is  the  smallest  body  conceivable  which  retains  the  iden- 
tity of  the  substance,  and  this  molecule  is  formed  by  two  or  more 
atoms  or  elem.ents.  An  atom  is  an  element.  The  atoms  are  united 
to  one  another  in  certain  relations  which  form  the  different  sub- 
stances with  which  we  are  familiar ;  thus  alcohol  is  expressed  by  its 
molecular  symbol  CaH^O,  which  means  that  two  atoms  of  carbon, 


108  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

six  atoms  of  hydrogen  and  one  atom  of  oxygen  are  united.  Now 
if  a  fluid  containing  a  limited  quantity  of  this  alcohol  (less  than 
15  per  cent.)  is  planted  with  the  acetic  acid  bacteria  in  the  presence 
of  atmospheric  oxygen,  the  germs  will  use  from  the  alcohol  two 
atoms  of  hydrogen  and  from  the  air  two  atoms  of  oxygen,  and  the 
j  result  is  that  the  alcohol  is  changed  into  acetic  acid  and  water  thus : 
CoHeO  +  02  =  C2H4O2  +  H2O. 
Alcohol  +  Oxygen  --=^  Acetic  acid  -j-  Water. 
Substances  undergoing  micro-decomposition  usually  contain 
various  species  of  bacteria  and  the  chemical  compounds  produced 
are  often  very  complex  for  the  reason  that  each  species  may  be 
transforming  the  same  substance  into  characteristic  compounds,  and 
the  acids  and  compounds  formed  by  one  species  may  be  attacked 
and  changed  by  a  different  species  into  different  compounds.  For 
instance,  the  yeast  plants  may  be  producing  alcohol  by  their  action 
on  glucose,  and  at  the  same  time  the  acetic  acid  group  will  seize  on 
the  alcohol  produced  and  convert  it  into  acetic  acid,  and  this  acid 
I  may  be  attacked  by  still  another  species  and  converted  into  car- 
bonic acid  and  water.  In  order  _to^  study  with  accuracy  th^c^m- 
[  pounds  formed  by  a  given  species  it.is  evident  that  pure  cultures  o£ 
that  species  must  be  obtained  and  grown  in  a  favorable  nutrient 
medium.  The  separation  of  pure  cultures  is  comparatively  easy  by 
the  methods  established  by  Dr.  Koch  of  growing  them  in  solid  media 
such  as  gelatin  and  agar,  which  confines  the  different  species  to 
isolated  positions  where  they  may  be  transplanted  to  other  media 
in  unmixed  cultures. 

There  are  usually  several  products  resulting  from  the  vital 
activity  of  a  given  species,  thus  the  yeast  plants  produce  alcohol, 
carbonic  acid,  succinic  acid,  glycerin  and  some  volatile  acids.  There 
are  many  varieties  of  yeast  plants  which  produce  these  products  in 
varying  quantities;  some  species  yield  very  large  amounts  of  alco- 
hol and  are  specially  cultivated  for  brewing,  baking,  etc.  The 
products  elaborated  by  them  depend  largely  upon  the  material  in 
which  they  are  growing,  and  this  is  true  of  all  bacteria  as  well. 
i  Vital  activity  goes  on  as  long  as  fresh  material  is  added  until  a 
j  certain  per  cent,  of  waste  product  is  produced,  when  they  cease  to 
'  perform  their  functions ;  then  they  become  dormant  or  actually  die 
under  the  influence  of  the  chemicals  formed  during  vital  activity. 
Thus  the  yeasts  will  multiply  until  about  15  per  cent,  of  alcohol 
is  produced.  In  addition  to  the  products  mentioned  above  the 
yeasts  or  saccharomyces  produce  an  enzyme  which  is  a  soluble  fer- 
ment capable  of  producing  alcoholic  fermentation  after  the  germs 
are  dead,  if  placed  in  fresh  nutrient  media.  There  are  a  number  of 
molds  which  produce  alcohol  and  various  acids  when  submerged 
in  fermentable  materials.    Oxygen  is  required  in  large  quantities  by 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  109 

the  molds  and  when  this  is  cut  off  by  exckiding  the  atmosphere, 
they  seize  the  oxygen  which  is  in  combination  and  a  true  fermenta- 
tionTl'esembnhg  tliat  of  yeasts,  is  produced.    The  free  admission  of 
atmospheric  oxygen  lessens  the  fermentation,  since  this  requirement 
is  more  easily  appropriated  than  that  which  is  in  chemical  combi-    ^"^ 
nation.     The  fermentation  will  be  accomplished  completely  in  a 
longer  time,  however,  since  the  evolution, of  gas  formed  cuts  off 
the  supply  of  atmospheric  oxygen  and  the  chemical  combinations 
are  broken  down  for  their  supply.     The  vacuum  therefore  is  a| 
good  condition  for  alcoholic  fermentation.     Multiplication  is  not  soj 
prolific  but  fermentation  is  more  violent  and  considerable  heat  is 
generated,  due  to  the  breaking  up  of  molecules  and  the  formation 
of  new  chemical  compounds.    Alcoholic  fermentation  was  formerly 
allowed  to  go  on  slowly  for  months  in  the  breweries,  but  the  process 
has  been  greatly  shortened  by  the  vacuum  process.     The  vacuum  |> 
pumps  are  set  to  work  and  the  oxygen  and  gases  are  pumped  away      ^ 
from  the  fluids,  thus  compelling  the  yeast  to  break  up  the  sugar] 
more  rapidly,  for  their  supply  of  oxygen. 

A  great  many  bacteria  which  grow  naturally .  and  luxuriantly 
in  the  presence  of  air,  are  thus  enabled  to  cause  more  violent  fer- 
mentation when  air  is  excluded  or  when  they  are  compelled  to  grow 
in  vacuo.  Thus  we  see  that  a. .vacuum  has  no  value  as  a  means  / 
of  preventing  fermentation.  In  canning  fruits  and  vegetables  in 
tin  cans  a  vacuum  is  desirable,  not  for  the  prevention  of  fermenta- 
tion but  to  cause  the  ends  to  draw  in  after  the  sterilizing  process. 
During  this  process  the  ends  of  tin  cans  become  bulged  and  unless 
a  vacuum  is  present,  after  cooling  they  draw  in  very  slowly  or  not 
at  all.  The  vacuum  is  produced  by  heating  the  contents  before 
finally  sealing  the  cans  or  by  mechanical  means,  the  power  depend- 
ing upon  the  heat  and  fullness  of  the  cans.  The  expansion  of  fluids 
is  greatest  at  or  near  the  boiling  points  and  on  cooling  there  is 
a  corresponding  contraction.  When  cans  are  not  filled  full  and  the 
contents  are  quite  Jiot  the  vacuum  formed  on  cooling  has  great 
power,  often  causing  the  cans  to  collapse.  The  vacuum  may  be 
regulated  by  attention  to  the  heat  and  fullness  of  the  can.  A  tem- 
perature of  1 80°  F.  and  filling  as  full  as  possible  will  produce  a 
vacuum  of  sufficient  power  for  all  practical  purposes.  The  vacuum 
has  value  in  the  detection  of  swells;  cans_which  do  not  draw  m  are 
likely  to  be  either  leaks  or  swells.  In  this  connection  I  want  to 
call  attention  to  the  misrepresentations  of  certain  manufacturers  of 
vacuum  machines.  Recently  a  circular  reached  me  giving  glowing 
accounts  of  a  machine  capable  of  sealing  in  vacuo  thousands  of 
cans  daily,  doing  away  entirely  with  the  sterilizing  process,  and 
claiming  great  saving  in  steam  and  labor  and  the  preservation  of 
natural  flavors.    The  whole  process  was  described,  which  consisted 


110  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


Saccharomyces  Cerevisiae 

Origin. — Beer  or  bakers'  yeast;   also   found  in  the  air. 

Co /or.— White. 

Form. — Cells  spherical  or  egg-shaped  8-iO;x  broad ;  they  are  colorless, 
and  have  a  homogeneous  protoplasm  when  actively  growing.  Granules  and 
vacuoles  develop  later.  Zoogleal  masses  may  be  formed,  owing  to  a  gela- 
tinous exudate.  The  cells  are  sometimes  single,  sometimes  they  have 
several  buds ;  long,  branching  forms  are  found  at  times,  especially  above 
30°. 

Motility. — Is  not  motile. 

Sporulation. — Several  spores  form  usually.  These  may  be  double 
stained.     They  develop  between  11°  and  72,°  c. 

Anilin  Dyes. — Stain  readily,  as  does  also  Gram's  method. 

Growth. — Thick  white  growth,  which  is  particularly  abundant  on 
glucose  media  and  in  wort. 

Gelatin  Plates. — The  colonies  are  small,  white,  opaque,  circular  in 
shape,  very  coarsely  granular  and  slimy. 

Stah  Culture. — There  is  a  thick  white  growth  on  the  surface.  No 
growth  in  lower  portion. 

Streak  Culture. — On  agar  and  on  potato  a  thick,  somewhat  raised, 
white  growth  is  formed. 

Temperature. — Fermentation  takes  place  most  rapidly  between  14° 
and  18°  C,  as  an  upper  yeast. 

Behavior  to  Gelatin.     Does  not  liquefy. 

Aerogenesis. — A  ferment,  invertin,  is  formed  which  changes  cane-sugar 
into  glucose.  The  latter  is  then  changed  to  carbonic  acid  and  alcohol 
(4-6%)    by  another  ferment    (zymase).     Does  not  ferment  lactose. 

Pathogenesis. — No  effect  on  animals.  A  catharrhal  condition  may  be 
produced  in  the  alimentary  tract  by  a  large  amount. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  Ill 

Plate  27 

Saccharomyces  cerevisice,  showing  budding  cells.     Potato  culture,     x  1000. 


*t   , 


►•    . 


Saccharomyces  cerevisice.     Culture  on  plaster  service.     Stained  with  carbol-fuchsin  and  methylene-blue.    x  1000. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  113 

of  putting  raw  fruits,  veg:etables,  meats,  etc.,  in  patent  cans,  which 
were  run  into  the  vacuum  machine  where  the  air  was  completely 
exhausted  and  the  sealing  was  done  in  vacuo.  I  wrote  these  parties, 
requestmg  a  detailed  account  of  their  process,  for  I  supposed  that 
there  must  be  some  sterilizing  process  connected  with  it,  but  to  my 
astonishment  they  claimed  that  the  vaccum  produced  was  all  that 
was  necessary.  There  are  a  number  of  canners  who  look  upon  a 
vacuum  as  a  necessary  condition.  The  fact  is,  however,  that  a 
vacuuiii.is  one  of  the  best  conditions  for  decomposition  when  cer- 
tain species  of  living  bacteria  and  spores  are  present. 

the:  vacuum  the:ory. 

There  seems  to  be  such  a  widespread  misconception  of  the  true 
value  of  a  vacuum  in  canned  goods  that  a  careful  study  of  the 
theory  may  not  be  out  of  place  at  this  time.  Occasionally  new  ma- 
chines are  advertised  for  packing  all  sorts  of  goods  by  the  "vacuum 
method,"  the  advertisement  reading  that  goods  are  superior  in  flavor 
and  require  less  cooking,  perhaps  none,  if  this  or  that  method  is 
employed.  In  years  gone  by,  nearly  every  packer  believed  that  a 
vacuum  in  his  cans  was  absolutely  necessary  for  perfect  keeping 
of  thegoods.  The  method  generally  adopted  for  obtaining  the 
vacuum  was  to  heat  the  cans  in  boiling  water  with  vent  holes 
open;  the  cans  were  then  taken  out  and  the  holes  were  soldered  or 
''tipped,"  after  which  the  cans  were  ready  for  sterilization  or  the 
final  process.  Another  method  was  to  seal  the  cans  completely; 
then  they  were  given  five  or  ten  minutes  boiling,  after  which  each 
can  was  punctured  with  an  awl,  thus  permitting  the  steam  and 
gases  (if  any  were  present)  to  escape;  then  the  awl  holes  were 
quickly  closed  prior  to  the  sterilizing  process.  This  method  was 
called  venting.  The  object  of  these  two  methods  was  two-fold, 
viz.,  to  drive  off  any  gases  present  and  to  expand  the  contents  by 
heat,  so  that  a  vacuum  would  form  by  contraction  after  cooling. 
Another  method  which  is  used  largely  today,  is  to  heat  the  goods 
before  filling,  then  the  cans  are  sealed  while  hot,  and  when  they^ 
are  cooled  off  after  sterilization  a  vacuum  is  necessarily  produce 
by  the  physical  law  of  contraction. 

It  is  very  convenient  and  necessary  that  a  vacuum  be  formed 
in  tin  cans  so  that  the  ends  will  draw  in  after  the  sterilizing  pro- 
cess. It  would  be  impossible  to  drive  the  ends  back  in  some  cases 
(depending,  of  course,  upon  the  goods)  unless  this  vacuum  w^ere 
formed.  There  is  one  exception,  that  is,  cold  packed  tomatoes ;  but 
this  cannot  be  called  a  true  exception,  because  the  tomatoes  are 
generally  warmer  during  the  canning  than  they  are  after  the  cans 
have  been  passed  through  the  final  process  and  allowed  to  cool. 
Even  then  it  is  necessary  at  times  to  force  the  ends  back  to  their 


114  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

natural  position;  this  is  called  "snapping."  It  is  generally  thought 
by  packers  that  all  cans  are  sound  which  give  evidence  of  a  vacuum, 
and  this  idea  has  given  rise  to  the  belief  that  a  vacuum  actually 
keeps  the  goods  from  spoiling.  It  is  indeed  surprising  how  gen- 
erally this  error  has  crept  into  the  minds  of  packers  and  certain 
manufacturers  of  vacuum  machinery,  too.  Only  two  years  ago  a 
certain  manufacturer  declared  to  me  that  he  was  able  to  reduce  the 
time  of  sterilization  by  twenty  to  twenty-five  per  cent.  He  claimed 
to  have  the  records  to  prove  that  his  assertions  were  correct.  An- 
other manufacturer  distributed  broadcast  a  circular  describing  his 
new  vacuum  machinery,  by  means  of  which  he  claimed  to  be  able 
to  can  fresh  fruits  and  vegetables  without  heating  (as  far  as  I  was 
able  to  learn),  and  these  he  claimed  would  keep  indefinitely  with- 
out fermenting  or  decomposing.  This  machine  was  manufactured 
in  Chicago,  and  its  maker  claimed  that  two  canning  houses  were 
running  40,000  cans  daily  by  this  method.  I  wrote  to  him  and 
warned  him  of  the  results  which  must  surely  follow,  and  told  him 
if  I  did  not  comprehend  his  system  fully,  I  would  be  pleased  to  be 
corrected.  His  reply  contained  the  same  claims,  but  I  have  never 
heard  of  the  two  canneries  who  were  putting  out  40,000  cans  daily 
with  his  machine. 

There  are  some  machines  on  the  market  which  have  _SDme  merit 
as  vacuum  machines,  because  they  exhaust  the  air  from  the  cans 
while  the  contents  are  cold.  This  system  is  particularly  attractive 
for  some  goods,  such  as  rrleats ;  it  accomplishes  the  same  purpose  as 
the  old  venting  method,  aitid  the  cold  cans  are  more  easily  handled. 
By  the  old  method  it  was  necessary  to  heat  the  cans  through  to  the 
center,  which  required  a  prolonged  venting  process.  Every  canner 
of  meats  remembers  the  time  when  the  whole  place  was  smeared 
with  the  grease  which  sqtiirted  out  from  the  awl  holes  necessary 
in  venting.  The  modern  vacuum  machine  entirely  does  av/ay  with 
all  that  extra  labor,  inconvenience  and  unsightliness.  This  vacuum 
machine  is  made  with  a  circular  chamber,  into  which  a  dozen  or 
more  cans  are  carried  around  a  sprocket  wheel.  When  the  ma- 
chine is  filled  the  chamber  is  closed  and  the  air  is  exhausted  by 
a  vacuum  pump.  Each  can  has  been  previously  capped,  but  the 
vent  hole  is  left  open,  and  the  air  is  exhausted  from  the  cans  through 
the  vent  holes.  Near  the  vent  hole  is  placed  a  small  button  of  solder 
with  the  necessary  flux,  and  as  the  cans  revolve  they  pass  under 
a  window  and  are  tipped  in  vacuo  by  means  of  a  tipping  iron  heated 
by  electricity.  The  iron  is  not  automatic  but  is  controlled  by  the 
operator  from  the  outside.  A  small  electric  light  inside  the  chamber 
furnishes  the  illumination.  As  each  can  is  brought  under  the 
window  the  small  piece  of  solder  is  melted  over  the  vent  hole. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  115 

When  the  cans  are  all  tipped,  the  vacuum  is  released,  and  the  cans 
are  carried  out  of  the  machine  and  carefully  inspected  for  leaks. 

As  we  have  stated,  the  value  of  this  device  is  the  saving  of 
time  and  the  neatness  of  the  work.  It  does  not  decrease  the  time 
required  for  sterilization,  but  does  save  the  expense  of  venting. 

The  vacuum  has  no  advantage  as  a  means  of  shortening  the 
sterilization  of  any  canned  goods.  To  understand  this  thoroughly 
let  us  study  the  character  of  the  bacteria  which  are  responsible  for 
the  spoilage  of  canned  goods.  There  are  a  great  number  of  bac- 
teria yeasts  and  molds  which  will  cause  chemical  changes  in  can- 
ned goods  unless  they  are  destroyed  by  sterilization. 

Nearly  all  the  bacteria  which  cause  the  spoilage  of  canned 
goods  after  incomplete  sterilization  are  spore-bearing  organisms. 
If  there  should  happen  to  be  a  leak  in  the  can,  or  should  processing 
be  neglected,  non-sporating  varieties  would  set  up  decomposition. 
Non-sporulating  varieties  are  always  destroyed  at  boiling  tempera- 
ture (212°  F.)  All  spore-bearing  bacteria  which  are  responsible 
for  spoilage  in  canned  goods  are  either  anaerobic  or  facultative 
anaerobic;  that  is  to  say;  some  are  able  to  grow  only  when  oxygen 
is  entirely  absent,  and  some  are  able  to  adapt  themselves  to  either 
condition.  The  vacuum,  then,  is  an  ideal  condition  for  the  growth 
of  anaerobic  bacteria,  because  the  stronger  the  vacuum,  the  better 
the  environment.  The  least  trace  of  oxygen  interferes  greatly  with 
the^  multiplication  of  these  germs.  When  we  speak  of  oxygen  in 
this  connection,  we  mean  free  oxygen  as  it  is  found  in  the  atmos- 
phere. The  anaerobic  bacteria  do  require  oxygen,  but  not  in  the 
free  state;  their  supply  is  always  obtained  from  molecules  of  nutrient 
substances  which  have  oxygen  chemically  combined  with  other 
atoms.  In  chemistry  we  speak  of  any  substance  as  being  made  up 
of  molecules^  and  the  molecules  as  being  made  up  of  atoms  chem- 
ically combined.  A  molecule  is  defined  as  a  very  small  particle  of 
matter  which  has  all  the  characteristics  of  the  natural  substance; 
for  instance,  a  molecule  of  sugar  is  the  smallest  particle  which  has 
all  the  characteristics  of  sugar.  A  molecule  cannot  be  farther  di- 
vided without  destroying  its  character.  Thus  we  may  illustrate 
CfiHigOn  is  a  molecule  of  grape  sugar  which  is  fermented  by  the 
lactic  acid  bacteria  will  be  divided  thus : 

Grape  Sugar]  ^  (Lactic  Acid 
which  would  read  thus :  One  molecule  of  grape  sugar  is  divid- 
ed into  two  molecules  of  Lactic  Acid.  A  molecule  is  composed  of 
natural  elements  called  atoms,  and  each  atom  is  designated  by  a 
letter,  thus  CqH-^^^^c  rneans  that  a  m.olecule  of  grape  sugar  is  com- 
posed of  6  atoms  of  Carbon,  12  atoms  of  Hydrogen  and  6  atoms 
of  Oxygen,  and  when  this  combination  is  broken  up  other  sub- 


116 


CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


Stances  are  formed.  As  we  have  shown,  the  molecule  of  grape 
sugar  is  changed  by  lactic  ferment^ition  into  two  molecules  of 
Lactic  Acid.  Now  if  we  let  grape  sugar  ferment  under  the  in- 
fluence of  yeast  or  mold  the  following  takes  place : 

CeHisOo  ]        f  2  QHoO      I  ^  f2  CO2 

1  mol.  grape  sugar  j  [2  mols,  alcohol  j  [2  mols.  of  carbon  dioxid 

Then  again  if  we  let  grape  sugar  ferment  under  the  influence 
of  the  Acetic  Acid  bacteria  we  have  the  following: 
C^H.^Oe  )         (3  C,H,0, 

I  mol.  grape  sugar/        I3  mols.  of  acetic  acid 

These  chemical  equations  illustrate  the  fact  that  a  molecule  is 
entirely  changed  in  character  when  it  is  divided.  This  gives  a 
splendid  idea  of  chemical  changes  brought  about  by  different  organ- 
isms, although  in  reality  they  are  still  more  complicated,  so  that 
instead  of  Alcohol,  Lactic  or  Acetic  Acid  being  formed  alone,  there 
are  usually  several  other  complex  substances  formed  at  the  same 
time,  such  as  glycerin,  succinic  acid  and  volatile  fatty  acids. 


Plate  28.     Aspergillus  Glaucus 

Aspergillus  Glaucus,  showing  the  conidia  on  the  tufts  or  sporangia.     Magnified  350  diameters 


Our  readers  will  notice  that  in  the  fermentation  of  grape  sugar, 
the  different  atoms  are  torn  apart,  and  the  particular  organism 
responsible  for  the  fermentation  uses  the  elements  for  its  propaga- 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  117 

tion.  Nothing  is  entirely  lost  chemically  and  although  carbon, 
hydrogen  and  oxygen  are  used  to  build  up  cell  protoplasm,  those 
elements  unite  promptly  to  form  the  products  elaborated  by  the 
germs,  and  of  course  are  characteristic  of  them. 

The  Anaerobic  bacteria,  therefore,  obtain  their  supply  of  0x3^- 
gen  from  chemical  combinations.  This  is  true  also  of  other  bacteria 
which  are  forced  to  grow  in  an  anaerobic  condition.  The  process 
of ^  decomposition  is  therefore  more  complete  where  the  air  is  en- 
tirely excluded  from  such  micro-organisms,  and  the  vacuum  in 
the  cans  is  a  favorable  environment.  The  molds,  yeasts  or  bacteria, 
which  consume  large  quantities  of  oxygen,  must  obtain  that  element, 
consequently  a  much  larger  quantity  of  material  must  be  changed 
quickly  for  the  supply  of  oxygen.  In  such  cases  the  number  of 
germs  present  is  quite  small  in  comparison  to  the  amount  of  ma- 


Plate  29.     Aspergillus  Glaucus 

Photomicrograph  of  the  beautiful  mold  plant  Aspergillus  Glaucus.  The  fruit  hyphae  showing  the  bottle- 
shaped  sterigmae  radiating  from  the  columellae  and  the  conidia  are  plainly  visible.  This  is  an  unstained  speci- 
men mounted  in  glycerine  and  photographed.     Magnified  500  diameters. 

terial  which  is  undergoing  chemical  change.  Oxygen  is  more 
difficult  for  bacteria  to  obtain  when  they  are  forced  to  grow  in 
a  vacuum,  because  large  quantities  of  material  must  be  deprived  of 
oxygen.  Decomposition  is  generally  pretty  well  advanced  when 
spoilage  is  noticed  in  canned  goods,  because  the  vacuum  of  the  can 
has  deprived  the  bacteria  of  free  oxygen.  Sterilization  must  there- 
fore be  complete,  if  goods  are  to  be  kept  pure  and  unfermented  in 
tin  cans  or  glass.  The  vacuum  has  absolutely  nothing  to  do  with 
the  keeping  quality  of  the  goods,  and  we  might  add  that  the  vacuum 


118  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

is  a  favorable  condition  for  decomposition,  unless  sterilization  is 
complete. 

"^  Test  tubes  containing  beef  juice,  corn  juice,  peas,  etc.,  are 
easily  sterilized  with  only  a  cotton  plug  in  the  top;  there  is  no  va- 
cuum, but  the  germs  from  the  air  are  filtered  out  by  the  cotton. 
This  is  the  method  used  in  the  laboratory  for  sterilizing  culture 
media. 

Any  canner  may  test  the  value  of  a  vacuum  for  himself  as 
follows :  Take  a  can  of  any  perfectly  sterilized  goods,  heat  an  awl 
in  a  flame  until  it  is  red,  heat  a  small  surface  of  the  can,  holding 
flame  directly  onto  it;  then  punch  a  hole  in  the  can  without  re- 
moving flame,  then  seal  the  hole.  The  vacuum  will  suck  air  into 
the  can  through  the  awl-hole  but  the  air  must  pass  through  the 
flame  which  destroys  all  molds  and  bacteria.  Although  the  va- 
cuum has  been  destroyed  by  the  admission  of  heated  air,  the  con- 
tents of  the  can  will  remain  in  an  un fermented  condition. 

CONCLUSIONS. 

Molds,  yeasts,  anaerobic  bacteria  and  bacteria  which  are  facul- 
tatively anaerobic,  will  grow  in  a  vacuum,  on  a  nutrient  medium. 
There  is  no  such  condition  as  an  absolute  vacuum  in  nature,  but 
there  may  be  a  condition  where  there  is  a  partial  vacuum,  where 
atmospheric  oxygen  is  entirely  absent  or  replaced  by  some  other 
gas.  A  vacuum  will  not  prevent  decomposition.  Decomposition  by 
bacteria  is  more  complete  when  air  is  entirely  excluded  from  can- 
ned goods.  Sterilization  cannot  be  accomplished  in  any  less  time 
in  the  presence  of  a  vacuum,  since  it  requires  a  certain  amount  of 
heat,  which  must  be  applied  for  a  given  time,  to  destroy  spores  of 
bacteria,  yeasts  and  molds. 

VALUE  OF  VACUUM  MACHINERY. 

Vacuum  machinery  may  have  some  advantage  over  other  meth- 
ods of  obtaining  an  exhaustion  of  air,  viz.,  goods  may  be  handled 
cold  and  considerable  labor  of  venting  is  saved.  For  reducing  the 
bulk  of  any  goods  such  as  milk  where  a  high  temperature  is  liable 
to  injure  the  flavor,  a  vacuum  is  valuable  for  removing  the  atmos- 
pheric pressure,  so  that  ebullition  may  take  place  at  a  comparatively 
low  temperature.  Evaporation  by  this  method  has  no  value  as  a 
sterilizing  process  where  spore-bearing  bacteria  are  present;  it  re- 
quires the  high  temperature  to  destroy  spores  and  the  vacuum  sys- 
tem cannot  give  successful  results  in  any  less  time  than  is  actually 
required  where  that  condition  is  absent.  Goods  like  milk,  which 
are  condensed  by  boiling  in  vacuo,  are  not  sterilized,  but  are  pre- 
served by  sugar  which  must  be  added  up  to  50  per  cent,  in  some 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  119 

cases.     Sugar  is  a  preservative  when  used  in  large  quantities,  be-  ! 
cause  it  takes  up  the  fluids.     Bacteria  require  fluids  for  multipHca- 
tion,  so  when  sugar  is  used  in  excess  the  spores  are  deprived  of  I 
fluid,  and  therefore  remain  dormant,  but  are  not  destroyed.  I 

Before  closing,  let  me  remark  that  no  vacuum  pump  is  able  to 
remove  all  bacteria  from  any  goods.  It  may  remove  a  large  num- 
ber from  the  small  air  space  at  the  top  of  a  package,  but  it  can- 
not exclude  those  forms  which  are  in  the  goods  themselves. 


Plate  30.     Saccharomyces  Ellipsoideus 

Photomicrograph  of  a  wild  yeast  or  wine  ferment  Saccharomyces-Ellipsoideus  (Hansen)  rounder  oval  cells, 
which  produce  spores  2  to  4  microns  in  diameter,  two  or  four  being  found  in  a  single  ascus.  It  forms  a  delicate 
surface  film  in  about  two  weeks  at  75  degrees  Fahrenheit.  It  produces  a  rapid  and  powerful  fermentation,  with 
formation  of  great  quantities  of  carbonic  acid  gas.     Magnified  800  diameters. 

The  yeasts  and  molds  are  not  the  only  species  which  produce 
alcoholic  fermentation;  there  are  a  number  of  bacteria  which  con- 
vert glycerin  media  into  alcohol ;  the  typhoid  and  pneumonia  bacilli, 
also  a  number  of  bacteria  found  in  the  mouth  and  on  the  teeth  have 
the  same  power.  Some  of  the  mucors  are  employed  in  pure  cul- 
tures in  the  manufacture  of  alcohol. 

The  yeasts  cannot  convert  starch  into  alcohol,  so  in  some  places 
molds  are  employed  to  convert  the  starch  into  sugar  and  the  yeast 
is  then  introduced  to  convert  the  sugar  into  alcohol.  In  the  manu- 
facture of  malt  beverages  and  vinegar  the  diastase  is  first  employed 
to  convert  the  starch  into  sugar  and  this  in  turn  is  converted  into 
alcohol  by  yeast.  Maltose  and  cane  sugar  are  changed  by  a  fer- 
ment produced  by  yeasts,  into  glucose,  which  in  turn  is  converted 
into  alcohol  and  the  by-products.  The  chemical  formulas  are  as 
follows : 


120  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

C12H22O11  +  H2O     I     ^     I  CcHisOc  +  CcH^gOe 
Cane  sugar  +  water  J  \  Dextrose  +  Levulose 

CcH.^Oe        )     _     UC2HeO  +  2C02 

Invert  sugar  J  |  Alcohol  +  Carbonic  acid 

The  use  of  glucose  in  jellies,  jams,  catsup  and  other  food 
products  is  therefore  fraught  with  danger.  The  atmosphere  is  laden 
with  wild  yeasts  which  easily  attack  the  glucose  and  fermentation 
quickly  follows.  It  has  been  customary  among  jelly  and  preserve 
makers  to  adulterate  the  juices  with  glucose  to  give  body  and  to 
sweeten  with  saccharin,  using  some  antispetic  to  retard  fermenta- 
tion. It  is  better  to  produce  pure  goods,  although  it  may  be  ad- 
visable in  some  cases  to  use  a  preservative,  but  the  label  should 
plainly  state  the  fact.  Large  quantities  of  glucose  are  mixed  with 
syrups  and  molasses  to  produce  mild  syrups,  the  object  being  to 
produce  a  syrup  of  milder  and  more  delicate  flavor  and  not  to 
adulterate.  These  syrups  are  hard  to  keep  and  should  be  sealed, 
hermetically  and  sterilized  and  not  preserved  with  antiseptics.  The 
manufacturers  of  syrups  have  a  great  deal  of  trouble  along  this 
line. 

ALCOHOLIC  FBRMBNTATJON  is  probably  the  most  use- 
ful chemical  change  accompli shedjby^jthe  lower  vegetable  orders. 
By  this  process  all  alcoholic  beverages  and  commercial  alcohol  are 
manufactured.  This  fermentation  is  accomplished  without  the  un- 
pleasant odors  and  flavors  so  characteristic  of  many  species  of  bac- 
teria. The  baking  industry  employs  the  yeasts  and  bacteria  of 
alcoholic  fermentation  to  produce  the  carbonic  acid  gas  for  raising 
or  inflating  what  would  otherwise  be  a  heavy  mass  of  dough. 

In  the  preparation  of  sauces,  catsups,  syrups,  jams,  preserves, 
jellies  and  food  products  of  like  nature  the  first  fermentation  is 
generally  alcoholic,  due  more  commonly  to  the  mold  fungi  but  often 
to  wild  yeasts  so  abundant  in  the  atmosphere.  The  seed  forms  of 
molds  (called  conida)  give  rise  to  this  fermentation. 

The  conida  are  small  round  spores  which  abound  on  the  tufts 
of  many  varieties  of  mold  and  when  they  are  submerged  will  bud 
and  multiply  similar  in  many  respects  to  the  true  yeasts  or  saccharo- 
myces.  Mold  naturally  grows  on  the  surface  of  media  which  have  a 
slight  acid  reaction,  and  its  oxygen  requirement  is  very  great.  So' 
long  as  free  oxygen  of  the  atmosphere  is  to  be  obtained  it  grows 
luxuriantly  without  causing  any  fermentation  of  the  lower  parts 
of  the  material  on  which  it  is  found,  but  if  the  oxygen  is  cut  off 
either  by  submerging  or  enclosing,  it  is  forced  to  obtain  its  oxygen 
requirement  from  the  molecules  in  which  oxygen  is  combined,  and 
new  compounds  are  thus  formed  and  a  fermentation  is  set  up  which 
in  many  respects  resembles  that  of  the  yeasts. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS. 


121 


Plate  31.     Mucor  Mucedo 

Photomicrograph  of  Mucor  Mucedo  in  the  living  state  mounted  in  glycerine.  The  round  pod  in  the  center 
contains  the  seed  forms  or  conidia.  This  pod  is  ripe,  ready  to  burst  when  the  conidia  are  carried  by  water  or 
air,  ready  to  start  a  new  mold  plant  or  to  set  up  fermentation  according  to  the  conditions  in  which  they  are 
thrown.     Magnified  800  diameters. 


no      (^ 


Plate  32.     Mucor  Mucedo,  showing  budding  conidia 

Photomicrograph  of  the  budding  conidia  of  Mucor  Mucedo,  obtained  from  a  jar  of  spoiled  tomatoes  under- 
going fermentation.  These  conidia  have  the  power  of  setting  up  a  fermentation  similar  in  many  respects  to  that 
of  the  yeasts.  In  this  manner  of  growth  Mucor  Mucedo  looks  very  much  like  the  brewers'  yeast  Sacharomoyces 
Cerevisiae.     Magnified  1,000  diameters. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  123 

Various  pulps  are  often  filled  into  barrels  hot,  with  a  small 
amount  of  antiseptic  to  prevent  fermentation,  but  on  cooling  quite 
a  large  air  space  is  left  above  the  surface  of  the  pulp  which  is  a 
rich  field  for  the  growth  of  mold.  After  the  formation  of  mold  the 
pulp  will  ferment  if  the  barrel  is  rolled  over  and  permitted  to  stand 
for  a  short  time  in  any  temperature  above  34°  F.  This  accounts  for 
the  large  losses  of  manufacturers,  who  load  and  ship  cars  of  bar- 
reled iDulp  from  one  place  to  another  during  the  spring  of  the 
year.  The  pulp  when  stored  away  in  cellars  remains  quiet  for 
months  and  appears  good,  but  too  frequently  the  mold  is  present, 
and  loss  follows  the  moving.  This  may  be  overcome  to  some  ex- 
tent by  boiling  pulp  down  to  20  per  cent,  solids  and  refilling  bar- 
rels after  cooling.  Pulp  stored  in  barrels  will  not  keep  unless 
a  small  amount  of  preservative  is  added.  The  loss  from  alcoholic 
fermentation  may  be  minimized  by  canning  the  pulp  in  large  tin 
cans  and  processing.  This  insures  a  far  better  quality  and  does 
away  with  the  necessity  of  using  antiseptics. 


Plate  33.     Acetic  Acid  Bacteria 

Photomicrograph  of  the  vinegar  bacillus,  Bacillus  Acidi  Aceti,  which  was  isolated  from  a  leaky  can  of 
tomatoes.  This  is  one  of  the  organisms  which  are  usually  found  in  the  "mother"  of  vinegar,  which  is  called 
Mycoderm  Aceti.  Solutions  containing  alcohol  in  amounts  less  than  15  per  cent,  are  fermented  and  the  alcohol 
is  converted  into  acetic  acid.  Stained  with  fuchsine  and  photographed  through  the  microscope.  Magnified 
1,200  diameters. 

ACETIC  ACID   I'ERMENTATION. 

Acetic  acid  fermentation  is  one  of  the  most  important  chem- 
ical changes  produced  by  bacteria.  Vinegar  is  the  chief  commer- 
ical  product  obtained,  and  while  as  yet  pure  cultures  of  bacteria 


124  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

are  not  extensively  employed  to  produce  it,  there  is  a  possibility 
that  present  methods  may  be  superseded  and  a  vinegar  of  greater 
strength  obtained  by  the  utilization  of  a  single  species  known  to. 
have  the  power  to  produce  a  higher  per  cent,  of  acetic  acid  than 
when  grown  in  company  with  other  organisms. 

There  are  a  number  of  bacteria  which  produce  acetic  acid 
when  grown  in  liquids  containing  not  more  than  15  per  cent,  alcohol. 
Pasteur  demonstrated  that  acetic  fermentation  was  due  to  the  living 
organisms  which  formed  slimy  scum  on  the  surface  of  alcohoHc 
fluids  such  as  beer,  cider,  wine,  etc.  This  scum  was  named  "My- 
coderma  aceti,"  which  means  "germ  skin  of  acetic  acid"  or  "mother 
of  vinegar."  It  is  a  zooglea  mass  of  various  bacteria,  such  as  Bac- 
terium aceti,  B.  Pasteurianus,  Bacillus  aceticus.  Bacterium  Kutz- 
ingianum,  etc. 

Acetic  fermentation  is  common  and  develops  rapidly  in  the^ 
alcoholic  fluids  when  exposed  to  the  atmosphere  at  a  temperature 
of  80°  to  85°  F.,  which  is  most  favorable.  Under  favorable  coiv" 
ditions  with  pure  cultures  14  per  cent,  acetic  acid  may  be  formed, 
wdiich  is  equal  to  140  grain  vinegar.  The  temperature  given  above 
must  be  lowered  after  the  acetic  germs  have  performed  their  funcr 
tions  to  prevent  oxidation  of  the  acetic  acid  and  water  by  the  bac- 
teria still  living  in  the  mycoderma.  The  chemical  equations  for 
these  two  changes  are  svmbolized  as  follows : 

1  ^CsHoO  +  O,  r-=  C0H4O2  +  H,0 
Alcohol  +  oxygen  =  Acetic  acid  -\-  water. 

2  =  C2H4O2  +  202  +  2  CO2  +  2  H2O 
Acetic  acid  -f-  Oxygen  =  Carbonic  acid  +  water. 

In  the  "mother  of  vinegar"  the  germs  are  united  very  closely 
by  mucinous  envelopes,  which  are  capsule-like  formations,  in  which 
the  bacteria  are  imbedded.  lodin  stains  these  envelopes  in  a  peculiar 
manner.  Those  of  B.  Pasteurianus  and  B.  Kutsingianum  are  stain- 
ed blue,  while  the  germs  themselves  arc  not.  The  envelope  of  B. 
Aceti  does  not  take  the  stain. 

At  the  temperatures  given,  80°  to  85°  F.,  involution  forms  oc- 
cur. 

By  involution  forms  we  mean  that  the  bacteria  change  from 
their  natural  forms,  as  shown  in  Fig.  30  and  form  threads  which 
are  very  much  smaller  in  places  and  have  no  resemblance  to  the 
normal  shapes. 

As  mentioned  before,  vinegar  is  the  chief  commerical  product 
of  these  germs,  and  vinegar  is  formed  from  liquors  containing  not 
more  than  15  per  cent,  alcohol.  Oxygen  is  absolutely  necessary  for 
these  organisms  and  they  consume  large  quantities,  and  for  this 
.reason  the  vinegar  spirit  is  diluted  with  vinegar  and  allowed  to  run 
slowly  over  beechwood  shavings  in  a  vinegar  generator,  thus  ex- 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS. 


125 


posing  the  large  surface  to  the  atmosphere.  These  beechwood  shav- 
ings are  sown  with  acetic  acid  bacteria  and  a  rapid  acidification 
follows.  By  this  exposure  large  quantities  of  alcohol  are  lost  and 
there  are  many  forms  of  bacteria  which  find  their  way  into  the 
spirit  along  with  the  acetic  acid  germs.  Parasites  such  as  Anguil- 
lula  aceti,  the  so-called  vinegar  eels,  and  Pythium  anguillulae  aceti, 
make  their  appearance  and  consume  both  alcohol  and  acetic  acid. 
There  are  many  people  who  have  the  opinion  that  these  parasites 
produce  acetic  acid,  but  such  is  not  the  case.  The  first  named  species 
is  the  more  common,  but  the  second  belongs  to  the  fungi  group  of 


"'^"4 


^dcten  VTK  Jo. it evr 1 0.170 in, 
y  100  0     (A-^fe,r  Hfl.n/c»t) 


45<tct.   fd/t  zcn^  I  a.  nurn 

Fig.  30.     Bacteria  found  in  the  Mycoderma  Aceti 

Oomycetes  and  these  destroy  the  first  species,  as  was  discovered  by 
Sadebeck.  The  utilization  of  pure  cultures  of  acetic  acid  bacteria 
has  not  been  accomplished  outside  the  laboratory,  but  there  is  no 
doubt  that  it  is  possible  and  practical.  A  vinegar  of  14  per  cent, 
acetic  acid  strength  may  be  manufactured  with  pure  cultures  from 
the  very  spirit  which  is  yielding  only  nine,  ten  and  eleven  per  cent, 
for  the  manufacturers  under  present  conditions. 

The  additional  yield  of  acetic  acid  means  a  great  saving  and  is 
worth  the  attention  of  manufacturers.  Pure  cultures  may  be  ob- 
tained easily  by  the  plate  culture  methods,  which  were  described  in 
Chapter  III.  The  spirit  can  be  sterilized  and  sown  with  the  pure 
culture  and  pure  oxygen  can  be  generated  and  forced  into  specially 
prepared  tanks  in  such  a  manner  as  to  exclude  all  foreign  bacteria 
and  parasites.  Vinegar  thus  prepared  will  be  of  great  strength 
and  promises  large  returns  for  the  successful  apparatus. 


^ 


126  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

The  old  method  known  as  the  Orleans  method  of  manufactur- 
ing vinegar  is  still  used  in  many  places.  The  method  is  thus  de- 
scribed by  Lafar,  page  397.  "A  number  of  oaken  casks,  each  of  a 
capacity  of  some  55  gallons,  are  arranged  in  rows  in  a  chamber 
maintained  at  a  constant  temperature  of  64°  to  71°  F.  In  the  upper 
part  of  the  head  of  each  cask  a  circular  aperture  is  provided,  through 
which  the  cask  is  filled  and  emptied  and  which  is  generally  kept 
closed  whilst  near  it  is  a  very  small  vent  always  left  open  for  the 
admission  of  air.  In  normal  work  each  cask  is  about  half  full.  Be- 
fore setting  a  new  cask  in  work,  it  is  scalded  out  several  times  with 
steam  or  hot  water,  in  order  to  extract  the  sap  from  the  wood,  and^ 
is^then  'soured'  by  impregnating  it  wath  good,  boiling-hot  vinegar. 
About  22  gallons  of  good,  clear  vinegar  on  less  than  ^  gallon  of 
wine  are  then  placed  in  the  cask,  another  V^  gallon  of  wine  being 
added  at  the  end  of  eight  days,  more  after  the  lapse  of  another 
week  and  so  on  until  the  cask  contains  40  to  44  gallons."  Vinegar 
is  then  drawn  from  the  cask  after  the  "mycoderma"  has  formed 
and  this  is  replaced  by  the  addition  of  wine.  The  cask  is  used  for 
several  years  when  deposits  are  so  heavy  as  to  necessitate^mptying 
and  cleaning." 


'%^'  • 


Plate  34.     Acetic  Acid   Bacteria 


Photomicrograph  of  Bacillus  Acidi  Aceti  or  Mycoderma  Aceti  or  "Mother  of  Vinegar,"  showing  short 
dumb-bell  rods,  large  lemon  shaped  and  drumstick,  involution  forms.  Produced  acetic  acid  in  tomatoes,  isolated 
by  plate  culture  method;  stained  with  fuchsine  and  mounted  in  xylol  balsam.     Magnified  1,000  diameters. 

The  slowness  of  this  method  is  apparent  and  the  opportunity^, 
for  contamination  by  injurious  bacteria  is  great.  There  are  enor- 
mous losses  of  alcohol  and  acetic  acid  and  the  quality  of  the  vin- 
egar is  often  very  poor.  This  process  was  improved  (?)  by  Pasteur 
in  1862,  who  cultivated  the  "mycoderma"  or  ''vinegar  flowers"  in 
small  vessels  and  transferred  this  to  the  surface  of  the  wine  in  vats 
kept  open  and  exposed  to  the  air  for  the  supply  of  oxygen,  but 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  127 

the  process  produces  various  results  due  to  contaminations  by  harm- 
ful bacteria.  Pasteur's  idea  of  cultivating  the  true  acetic  acid  bac- 
teria v^as  good,  but  the  apparatus  is  faulty.  For  this  reason  his 
methods  are  not  now  in  favor,  the  quick  vinegar  method  having 
taken  its  place  to  a  very  large  extent. 

These  two  processes  have  been  outlined  in  this  connection  mere- 
ly to  point  out  the  imperfections  in  them  and  not  to  describe  the 
best  method  of  manufacturing  vinegar.  By  the  present  methods 
it  is  plain  that  the  mixed  germs  emplo3^ed  in  acetic  fermentation 
do  not  accomplish  the  best  resits  and  that  there  is  considerable  loss 
in  alcohol  and  acetic  acid. 

In  general,  acetic  fermentation  causes  very  little  trouble  as  a 
source  of  spoilage  in  the  food  products  industry.  Wines  used 
in  table  sauces  and  soups  may  suffer  from  it  if  left  exposed  to- 
the  atmosphere  and  the  same  is  true  of  any  product  in  which  alco- 
hol is  present  not  to  exceed  15  per  cent.  Pulps  which  have  under- 
gone alcoholic  fermentation  either  on  account  of  wild  yeasts  or 
molds  will  also  undergo  acetic  fermentation  along  with  other  fer- 
mentations such  as  lactic  and  butyric.  Manufacturers  of  tomato- 
catsup  who  use  barrel  pulp  can  call  to  mind  numerous  instances 
where  the  pulp  had  turned  into  vinegar  and  other  complex  acids. 
The  preservers  have  some  difficulties,  too;  preserves,  apple 
butter,  peach  butter  and  light  syrup  goods  are  subject  to  slight  al- 
coholic fermentation,  unless  properly  handled  and  sterilized,  then 
acetic  fermentation  follows  with  the  loss  of  sugar. 

Dill  pickles,  pearl  onions  are  salted  with  just  enough  salt  to 
plasmolyze  the  harmful  organisms,  and  alcohol  is  generated  first, 
then  follows  acetic  and  lactic  fermentations  to  produce  vinegar 
having  a  characteristic  flavor. 

All  vinegar  having  a  certain  per  cent,  of  solids  in  liable  to 
deterioration  through  the  agency  of  harmful  bacteria,  hence  storage 
in  cool  places  is  recommended  for  such  as  malt  and  cider  vinegars. 


BUTYRIC   ^KRME:nTATION. 

There  is  a  recipe  for  butyric  fermentation  given  in  some  chem- 
istries, as  follows :  Put  into  a  10  per  cent,  sugar  solution  a  small 
quantity  of  chalk  and  cheese  and  keep  this  at  a  temperature  of  ^"j^ 
to  86°  F.  The  first  fermentation  that  starts  is  lactic  in  which  lactic 
acid  and  calcium  lactate  are  produced ;  the  next  is  the  butyric  fer- 
mentation which  is  set  up  by  an  anaerobic  organism  2/x  broad  and 
from  2 — 15/X  long,  which  was  discovered  by  Pasteur  in  1861. 
Pasteur  did  not  class  this  germ  as  belonging  to  the  bacteria  but 
considered  it  an  animalcule,  because  it  had  a  rapid  movement.  Its 
manner  of  vegetating,  however,  is  now  settled  and  it  can  positively^ 


128  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

be  said  that  it  belongs  to  the  fission  fungi,  because  it  multipHes  by 
lengthening  and  dividing  and  forms  spores.  It  is  endowed  with 
numerous  llagella,  growing  out  all  over  the  surface  of  the  cell  and 
by  means  of  these  its  rapid  motion  is  attained. 

There  are  a  number  of  bacteria  capable  of  producing  butyric 
acid,  some  of  which  are  anaerobic,  while  other  are  aerobic. 

Prazmowski  studied  the  cause  of  this  fermentation  and  de- 
scribes an  organism  which  corresponds  with  the  'Vibrion  butyrique" 
discovered  by  Pasteur  and  named  it  Clostridium  butyricum.  An- 
other germ  similar  in  many  respects  was  named  Butyricus  amylo- 
bacter,  which  is  so  named  because  the  cell  contents  resemble  starch 
which  turns  blue  with  iodin  staining.  So  closely  are  the  two  germs 
allied,  however,  that  I  believe  them  to  belong  to  the  same  family. 
In  1884  Hueppe  discovered  a  bacillus  which  grows  in  the  presence 
of  oxygen  which  he  named  Bacillus  butyricus  and  another  similar 
to  this  was  later  discovered  in  old  cheese  and  named  Clostridium 
foetidum,  while  from  milk  Bacillus  liodermos  has  been  obtained. 

In  butyric  fermentation  various  compounds  are  produced  such 
as  butyl  alcohol,  butyric,  acetic  and  carbonic  acids,  hydrogen  and 
sulphuretted  hydrogen,  etc.  The  fats  and  carbohydrates  are  sub- 
ject to  this  fermentation  and  a  chemical  equation  may  be  thus 
symbolized  to  show  the  decomposition  of  glucose  into  butyric  acid, 
carbonic  acid  and  hydrogen. 

Q-.Hi^Oel      fC.HgOo  -f  2CO2  +  2H2 

Glucose.  J     I  Butyric  acid  +  Carbonic  acid  +  Hydrogen. 

There  are  two  kinds  of  butyric  acid,  differentiated  in  organic 
chemistry  as  fermentation  butyric  and  isomeric  acid  or  isopropyl 
formic  acid,  which  is  not  obtained  by  fermentation;  both  have  the 
same  chemical  symbols  but  are  differently  arranged  in  atomical  re- 
lation. Butyric  acid  fermentation  can  be  observed  and  studied  by 
our  readers  by  boiling  a  small  quantity  of  milk  in  a  test  tube  and 
allowing  lactic  fermentation  to  take  place,  which  precipitates  calcium 
lactate,  which  is  attacked  by  the  butyric  acid  bacteria,  and  from  this 
cultures  may  be  obtained  by  the  plate  method. 

Butyric  bacteria,  whether  they  belong  to  the  aerobic  or  the 
anaerobic  species  form  spores  which  are  resistant  to  high  temper- 
atures. They  are  found  on  the  leaves  and  fibre  of  nearly  all  kinds 
of  vegetables  and  cereals  ready  to  set  up  butyric  decomposition 
whenever  the  conditions  are  favorable  for  their  development.  The 
cellulose  or  fibre  is  the  part  usually  decomposed  by  these  organisms. 
It  is  a  remarkable  fact  that  even  paper,  made  from  wood  pulp,  will 
dissolve  in  a  fluid  undergoing  butyric  fermentation.  It  must  not 
be  supposed  that  simple  butyric  acid  is  the  only  product  elaborated 
by  species  of  this  group  since  there  have  been  isolated  certain  or- 
ganisms which  produce  sweet-smelling  ethers  and  aromatic  sub- 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS. 


129 


Plate  35.     Bacillus  Butyricus  Amylobacter,   Flagellated 

Photomicrograph  of  Bacillus  Butyricus  Amylobacter,  an  aerobic  bacillus  which  when  grown  on  substances 
containing  starch  will  stain  blue  with  iodine.  The  flagella  are  very  curly  and  were  demonstrated  by  our  special 
method,  from  a  24  hours'  growth  on  2  per  cent,  glucose  agar  which  had  been  inoculated  from  the  juice  of  corn  in 
a  swelled  can.  This  organism  is  frequently  found  in  decomposing  vegetables  and  organic  matter,  and  is  not 
found  in  the  air.     Its  habitat  is  probably  the  soil.     Magnified  1,200  diameters. 


Plate  36.     Bacillus  Butyricus  Amylobacter.     Rods  and  Spores 

This  beautiful  photomicrograph  shows  the  free  spores  and  the  rods  containing  spores  of  Bacillus  Butyricus 
Amylobacter.  The  spores  are  generally  formed  in  the  center  of  the  rods  which  cause  them  to  swell  in  the  middle 
like  spindles,  hence  they  belong  to  the  type  called  "Clostridium."  The  spores  are  not  easily  destroyed  by  heat 
and  may  live  in  corn  which  has  received  a  temperature  of  250  degrees  for  nearly  one  hour.  Stained  with  car- 
bol  fuchsine.     Magnified  1,500  diameters. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  131 

Stances  which  are  vahiable  in  the  ripening  of  certain  kinds  of  cheese, 
Among  these  might  be  mentioned  Butyricus  Amylobacter  which  we 
considered  in  the  early  part  of  this  chapter,  and  Clostridum  foeti- 
dumelactis,  which  gives  the  flavor  to  Limburg  cheese,  also  a  sugar- 
loving  species  found  in  soft  country  cheese  called  bacillus  saccharo- 
butyricus.  Milk  generally  contains  the  spores  of  the  butyric  acid 
group,  and  it  is  due  to  them  that  the  disagreeable  odors  which  are 
associated  with  its  decomposition  are  set  free. 

We  make  mention  of  cheese  and  milk  and  the  bacteria  asso- 
ciated with  them  because  they  enter  largely  into  the  formulas  of 
special  food  products  such  as  soups,  macaroni  and  cheese  (salad 
dressings),  etc.,  sold  on  the  market  under  private  names.  There 
are  several  different  kinds  of  gases  evolved  where  butyric  fermen- 
tation is  going  on,  HgS  (sulphuretted  hydrogen),  C  Oo  (carbonic 
acid  gas),  CH.i  (methane  or  marsh  gas).  There  are,  however, 
some  species  which  do  not  produce  any  gas.  I  isolated  one  species 
from  cream  of  tomato  soup,  which  had  coverted  the  milk  sugar 
and  invert  sugar  directly  into  butyric  acid  without  swelling  the 
can.  This  species  corresponded  to  the  one  isolated  from  soft  cheese 
by  V.  Von  Klecki,  which  he  named  bacillus  saccharobutyricus  men- 
tioned above.  The  soup  had  been  given  a  process  of  250°  F.  for 
twenty-five  minutes;  the  spoilage  did  not  develop  until  a  lapse  of 
three  weeks.  It  was  found  by  experiment  that  one  hour  at  250°  F. 
was  necessary  to  destroy  the  spores  of  this  organism.  In  some  of 
the  cans  the  regular  well-known  species  w^ere  found,  but  the  cans 
were  swelled. 

Butyric  decomposition,  while  inimical  to  the  canner's  products, 
nevertheless  has  its  uses  in  nature,  and  in  some  industries.  It  plays 
an  important  part  in  the  preparation  of  brown  hay,  sweet  ensilage 
and  sour  fodder,  and  in  the  aging  of  manures.  In  the  retting  of 
flax  and  hemp,  the  cellular  substances  are'  dissolved  so  that  the  fibre 
can  be  obtained  in  the  pure  state. 

Butyric  decomposition  is  one  of  special  interest  to  canners  of 
peas,  string  beans,  asparagus,  celery,  corn  and  similar  vegetables, 
because  the  spores  of  different  types  of  butyric  bacilli  are  present 
on  surface  of  the  pods  and  fibres.  The  butyric  spores  are  usually 
ellipsoidal  in  form  and  not  quite  so  broad  as  the  mother  germ; 
they__3vithstand  dessication  remarkably  well  and  high  temperatures 
are  required  to  destroy  them.  There  are  some  other  kinds  of  spore 
bearing  germs  which  are  more  resistant  than  these,  but  not  many; 
250°  F.  for  a  few  minutes  will  destroy  the  spores,  but  in  order 
to  get  this  temperature  at  the  center  of  the  cans  the  nature  of  the 
contents  must  be  studied.  If  the  material  is  heavy  and  thick  and 
contains  much  fibre,  it  will  require  a  much  longer  time  than  when 
the  contents  of  the  cans  are  strictly  fluid.     The  exhausted  cans  are 


132  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

not  absolutely  without  oxygen  since  the  space  within  contains  some 
air,  consequently  strickly  aerobic  forms  may  be  able  to  set  up  de- 
composition. Usually,  however,  the  decomposition  is  set  up  by  an- 
aerobes and  facultative  anaerobes.  Since  almost  all  butyric  bac- 
teria belong  to  these  two  classes  the  conditions  in  canned  vege- 
tables are  specially  favorable  for  their  vital  activity. 

The  canning  of  such  vegetables  as  are  liable  to  butyric  j,e- 
composition  should  be  done  very  soon  after  they  are  harvested.  The 
growing  plants  are  not  favorable  for  the  invasion  of  these  bacteria 
and  it  is  only  after  they  are  harvested  and  attacked  by  other  germs 
such  as  the  lactic  acid  group  that  the  hardier  forms  begin  their 
work  of  destruction.  They  are  specially  active  on  vegetables  which 
are  par-boiled  and  allowed  to  stand  exposed  and  thus  demonstrate 
that  they  are  true  scavengers. 

The  development  of  spores  and  the  formation  of  spores  is  ac- 
complished in  from  thirty  to  forty-five  minutes  by  the  butyric  bac- 
teria when  every  condition  is  favorable.  When  partly  cooked  vege- 
tables are  allowed  to  stand  too  long  the  center  of  the  mass  will 
be  attacked  by  the  anaerobic  forms  while  the  aerobic  forms  on  the 
surface  are  thriving.  Those  on  the  surface  use  up  the  oxygen 
from  the  air,  at  the  same  time  set  free  various  gases  and  in  this  way 
create  the  most  favorable  conditions  for  the  development  of  the 
anaerobic  variety,  the  spores  of  which  are  scattered  within  the 
mass.  This  is  also  true  of  the  raw  material  which  is  piled  too  close- 
ly. Here  the  peptonizing  ferments  begin  to  vegetate  and  soften  the 
fibre,  causing  the  juices  to  ooze  through  their  protecting  sacs  and 
the  temperature  is  increased  so  that  the  appearance  of  the  vegetables 
resembles  par-boiling;  in  other  words,  they  look  as  if  they  were 
cooked.  This  is  the  condition  as  before  described  and  butyric  de- 
composition progresses  rapidly.  A  bitter  flavor  is  often  imparted 
I  to  such  vegetables  by  a  bacillus,  which  has  given  me  considerable 
trouble  to  isolate.  It  is  a  spore-bearing  bacillus  actively  motile, 
due  to  a  large  number  of  flagella.  The  spores  are  very  hardy,  re- 
quiring about  fifteen  minutes  at  250'^  F.  to  destroy  them.  They 
are  oval  and  located  in  the  center  of  the  rods  which  at  times  give 
the  bacillus  a  Clostridium  appearance.  The  development  of  the 
spore  is  similar  to  that  of  the  Bacillus  megatherium  of  De  Bary. 
The  young  rod  passes  out  of  the  spore  at  right  angles  to  the  long 
axis  of  the  spore  and  often  retains  the  spore  shell  at  one  or  both 
sides.  The  bacillus  is  from  2/x  to  6,ti  long  and  about  cS/x  to  if^ 
broad,  with  rounded  ends  similar  to  B.  subtilis.  Informs  butyric 
acid  and  coagulates  milk,  is  a  facultative  anaerobe  and  does  not 
cause  the  cans_to_ swell.  Cans  of  peas,  asparagus  and  string  beans 
inoculated  with  a  pure  culture  turn  quite  bitter  within  six  days. 
The  colonies  growing  on  agar  are  round  with  a  pale,  transparent. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  183 

very  delicate  zone  surrounding  them;  the  surface  is  white,  shghtly 
wrinkled,  becoming  more  so  with  age.  When  magnified  by  250 
they  are  yellowish  and  opaque.  The  deep  colonies  have  a  whet- 
stone appearance.     Grows  well  at  a  temperature  of  85°  to  90°  F. 

/\s  bitter  decomposition  has  caused  the  canners  considerable 
trouble  at  times  the  description  here  given  will  be  interesting.  The 
bacillus  may  produce  the  bitterness  in  the  raw  material  if  too  long- 
exposed  or  to  the  partially  cooked  products  if  allowed  to  stand  too 
Tong  before  the  final  process,  or  it  may  develop  in  the  cans  if  under- 
processed.  The  spores  are  destroyed,  however,  at  a  temperature  of 
250'^  F.  for  fifteen  to  twenty  minutes'  actual  heat;  time  required 
'for  penetration  of  can  and  the  contents  must  be  added  to  this. 

Frequently  X  have  noticed  that  goods  which  have  undergone 
chemical  changes  due  to  bacteria  have  no  living  bacteria  in  the  cans^ 
When  the  fluid  is  examined  under  the  microscope  there  are  numer- 
ous bacteria  present,  but  when  agar  or  gelatin  plates  are  inoculated 
there  would  be  no  growth.  These  bacteria  w^hen  mounted  fail  to 
take  the  stains  readily,  which  proves  that  they  are  dead.  This 
phenomenon  will  be  noticed  frequently  by  our  students  in  their 
researches  and  is  explained  in  two  ways;  either  the  bacteria. , were 
destroyed  during  the  sterilizing  process,  having  previously  accom- 
plished the  chemical  changes,  or  they  died  under  the  influence  of 
the  products  elaborated  by  themselves,  either  before  the  sterilizing 
process  or  more  likely  afterwards.  If  vital  activity  goes  on  after 
the  sterilizing  process,  the  amount  of  acid  produced  is  often  germ- 
icidal, and  this  may  be  accomplished  in  a  few  days ;  it  is  usually 
after  a  longer  time,  however,  varying  from  three  weeks  to  six 
months.  The  examination  of  spoiled  cans  should  be  made  as  soon 
as  possible  after  the  trouble  develops. 

A  great  deal  of  the  trouble  experienced  from  butyric  decom- 
position is  avoided  by  careful  attention  to  cleanliness.  Remember 
that  the  floors  and  machinery  will  be  covered  more  or  less  with 
accumulations  each  day  and  this  dirt  contains  the  elements  of  what 
you  are  packing.  Fai'lure  to  rernoye_such  accumulations  by  the  lib- 
eral use  of  soap  and  water,  and  at  times  a  powerful  disinfectant, 
only  invites  an  inimical  host  of  bacteria,  which  is  ready  to  attack 
the  fresh  j)roduct  which  is  being  canned.  The  jyaste  material 
should  be  moved  far  away  from  the  factory,  and  where  practical  it 
may  be  put  into  silos  and  converted  into  money  where  a  market 
is  offered  for  ensilage.  The  habit  many  packers  have  of  loading 
wheelbarrows  and  dumping  cobs,  husks,  pea-pods,  peelings  and 
waste  just  outside  of  the  factory  in  great  piles,  is  very  dangerous. 
Whife  you  may  have  been  successful  in  one  season  with  a  certain 
time  and  temperature  in  your  sterilizing  process,  you  may  have 
great  difficulty  during  the  next  season.     The  atmosphere  in  the 


134  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


Bacillus  3Iegfatherium,  De  Bary 

Origin. — Found  originally  on  boiled  cabbage  leaves ;  is  present  in  the 
air  and  in  the  soil;  it  is  also  found  on  other  vegetable  matter. 

Form. — Large  cylindrical  rods,  having  rounded  ends,  three  to  six 
times  as  long  as  broad,  and  with  granular  contents.  They  are  found  in 
pairs,  ordinarily  slightly  bent ;  they  may  form  threads.  Involution  forms 
are  quite  common,  and  capsulated  cells  are  especially  found  in  slimy 
growths. 

Motility. — They  have  six  to  eight  flagella,  and  have  a  slow,  creeping 
motion. 

Sporulation. — Median  spores  are  formed. 

Anilin  Dyes. — Stain  readily,  though  irregularities  may  be  seen  which 
are  due  to  granular  protoplasm. 

Grozvth. — Rapid. 

Gelatin  Plates. — Small,  irregular,  yellowish  colonies  are  formed,  which 
later  show  marked  branching  or  radiating  forms — these  soon  liquefy  the 
gelatin.     Sometimes  the  colonies  are  kidney-shaped. 

Stab  Cultures. — The  growth  is  rapid,  attended  with  liquefaction  along 
the  line  of  inoculation,  and  may  show  threads  of  bacteria  penetrating  out- 
ward into  the  solid  gelatin.  The  gelatin  becomes  wholly  liquefied  later, 
a  flocculent  mass  accumulating  on  the  bottom ;  the  liquid  clears  up  without 
any  formation  of  scum  on  top. 

Streak  Cultures. — On  agar,  a  dull  white  or  grayish  covering  is 
formed.  On  potato,  a  thick,  slimy,  grayish-white  mass  is  rapidly  formed, 
rich  in  spores  and  involution  forms. 

Oxygen  Requirements. — Aerobic. 

Temperature. — May  grow  in  incubator,  but  optimum  heat  is  at  about 
20°   C. 

Behavior  to  Gelatin. — Liquefies  rather  slowly. 

Pathogenesis. — No  effect  has  been  observed. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS. 


185 


Plate  37.     Bacillus  Megatherium,  Flagellated 

Photomicrograph  of  an  actively  motile,  spore-bearing  bacillus  which  belongs  to  the  Magatherium  group. 
It  was  isolated  from  some  pickles  to  which  it  had  imparted  a  most  disagreeably  acrid,  bitter  flavor.  It  requires  an 
acid  medium  for  luxuriant  growth,  diluted  malt  and  cider  vinegar  being  particularly  favorable.  The  numerous 
delicate  flagella  were  demonstrated  by  laboratory's  special  method,  from  an  eight-hours'  growth  on  acid  agar. 
Magnified  1,000  diameters. 


Plate  38.     Bacillus  Megatherium,  showing  Spores 

Photomicrograph  of  the  spore  or  seed  forms  of  the  pickle  bacillus  shown  in.  Plate  37.  The  spores  are 
large,  thick-walled,  and  are  formed  in  the  center  or  near  one  end  of  the  rod  and  are  rapidly  setf  ree.  Spore 
formation  takes  place  rapidly  in  24  hours.  From  an  agar  growth,  preparation  stained  faintly  with  carbol  fuch- 
sine  and  photographed  through  the  microscope,  using  Spencer  1-12  oil  immersion  objective  and  acetylene  radiant. 
Magnified  1,000  diameters. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  137 

neighborhood  of  your  factory  may  be  laden  with  the  spores  of  nevy 
varieties  of  hardy  bacteria  which  have  grown  hixiiriant]}[_pn  the 
piles  of  waste  in  the  yard.  These  find  entrance  to  yQiir-cans__and 
c^ompli'cations  arise,  goods  undergo  transformations,  and  you  are 
tempted  to  blame  Providence  for  your  losses.  The  canners  who 
are  alive  to  the  benefits  of  clean  floors,  machinery  and  tidy  employes 
and  who  remove  every  obnoxious  element  out  of  the  factory  and 
yard  are  really  the  men  who  experience  small  losses  from  spoilage, 
and  their  careful  methods  create  a  care  for  the  quality  of  the  goods 
they  pack  and  an  interest  in  the  selection  of  raw  material.  The  re- 
sult is  that  their  goods  bring  the  best  prices,  their  establishments 
are  open  to  the  public  and  the  whole  moral  effect  of  cleanly  meth- 
ods is  apparent. 

IvACTiC   I^KRMICNTATION. 

Lactic  fermentation  is  accomplished  by  a  large  number  of 
bacteria  and  is  one  of  the  most  useful  chemical  changes.  It  is  prob- 
ably the  earliest  known  form  of  decomposition,  since  milk  gives  a 
good  example,  and  milk  has  been  used  as  food  from  the  time  of 
creation  and  its  use  was  no  doubt  familiar  to  the  first  inhabitants 
of  the  earth.  In  the  early  days  of  the  microscope  forms  of  life 
were  noticed,  chiefly  those  belonging  to  the  w^ild  yeast  and  mold 
fungi ;  but  not  until  the  time  of  Pasteur  was  there  any  definite  un- 
derstanding as  to  the  true  cause  of  lactic  fermentation,  Jor  all 
theories  previously  advanced  attributed  the  changes  wrought  in  milk 
to  spontaneous  generation.  Lister  w^as  probably  the  first  investi- 
gator who  obtained  pure  cultures  of  Bacterium  lactis,  a  germ  seldom 
fotmd  outside  of  dairies.  Hueppe  followed  with  a  more  careful 
investigation  by  means  of  gelatin  plates  and  isolated  several  spe- 
cies of  bacteria  which  w^ere  capable  of  setting  up  lactic  decom- 
position. The  principal  organism  discovered  by  him  was  Bacillus 
acidi  lactici,  which  measures  i  to  1.7/A  in  length  and  0.3  to  0.4/-^  in 
breadth,  non-motile  rods,  usually  in  pairs.  Bodies  resembling  spores 
are  present,  but  they  are  not  true  spores,  although  so  considered 
by  some  authorities.  Casein  is  precipitated  and  carbonic  acid  gas 
isjiberateil  at  ordinary  temperatures.  Bacterium  Prodigiosum,  de- 
scribed under  head  of  Chromogenic  Bacteria,  Chapter  IL  produces 
lactic  acid. 

Micrococcus  acidi  lactic  (Krueger,)  found  as  single  or Jiplp- 
cocci,  is  aerobic,  forms  lactic  acid,  and  liquefies  gelatin. 

Bacterium  lactic  acidi.  Bacillus  lactis  acidi,  Bacterium  acidi 
lactis.  Bacterium  limbatum  lactis  acidi.  Micrococcus  lactis  acidi  and 
Sphaerococcus  lactis  acidi,  were  isolated  from  sour  milk  by  Alarp- 
man. 


138  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


Bacillus  Acidi  Lactici)  Hueppe 

Origin. — Found  in  sour  milk,  also  in  fermenting  vegetable  matter. 

Form. — Thick,  short  rods,  two  to  three  times  as  long  as  wide,  usu- 
ally found  in  pairs ;  but  rarely  found  in  chains  or  threads. 

Motility. — It  has  no  real  motion,  but  has  a  marked  Brownian  move- 
ment. 

Spondation. — Round,  terminal  bodies  have  been  observed,  but  are 
not  spores. 

Anilin  Dyes. — Stain  readily;  so  does  Gram's  method. 

Growth. — Rapid  and  abundant. 

Gelatin  Plates. — The  deep  colonies  are  oval  or  round,  yellow,  finely 
granular,  with  sharp  borders.  The  surface  colonies  spread  and  form 
thin  plaques,  having  irregular  wavy  borders.  The  outer  zone  of  the  colony 
is  almost  transparent  at  first,  showing  markings  which  resemble  the  veins 
in  leaves. 

Stab  Culture. — The  growth  on  the  surface  is  considerable,  spreading 
rapidly ;  it  is  a  thin,  dry,  white  covering ;  growth  along  the  puncture  is 
slight.  In  old  cultures  bundles  of  crystals  are  formed  along  the  line  of 
inoculation,  more  especially  at  or  near  the  surface. 

Streak  Culture. — On  agar,  a  grayish-white,  moist,  spreading  growth  is 
formed.     On  potato,   a  brownish-yellow,   slimy  growth   is   formed. 

Milk. — In  sterilized  milk,  the  lactose  is  converted,  in  part,  into  lactic 
and  carbonic  acids.  Casein  or  curd  is  caused  by  the  acid  reaction  thus 
produced.  The  change  will  occur  only  in  the  presence  of  air.  Old  cul- 
tures do  not  affect  milk. 

Oxygen  Requirements. — It  is  a  facultative  anaerobe. 

Temperature. — It  will  grow  between  io°  and  45°  C,  but  grows  best 
at  about  30°  C. 

Behavior  to  Gelatin. — Does  not  liquefy. 

Aerogenesis. — It  forms  gas  in  milk;  also  forms  carbon  dioxide  and 
alcohol. 

Pathogenesis. — It  has  no  effect.  Growth  is  stopped  by  0.75%  lactic 
acid.  It  produces  lactic  acid  in  the  mouth  (dental  caries)  ;  also  abnormal 
fermentations  in  the  stomach  and  intestines.  Lactic  acid  bacteria  promote 
the  growth  of  anaerobic  bacteria. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  139 

Bacillus  lactis  (Bleisch),  found  in  buttermilk  and  frequently 
n2^qrdinary  cream,  is  a  large  bacillus,  forming  spores  of  great  re- 
sistiiTg;  power.  It  is  a  facultative  anaerobic  actively  motile  organ- 
ism7  and  converts  glucose  into  lactic  acid  without  the  evolution  of 
gasT^The  bacillus  is  about  t/j.  broad  and  3  to  ^ij^  in  length  and 
may  be  cultivated  in  agar  plates,  or  on  a  substratum  of  cream  of 
tomato  soup.  The  specimen  shown  in  Plates  40  and  41  was  found 
in  a  can  of  sour  tomato  soup  in  which  no  gas  had  formed,  the 
sugar  having  been  broken  up  directly  into  lactic  acid.  On  Agar 
and  potatoes  it  forms  a  light  gray  coating. 


Plate  39.     Lactic  Acid  Bacilli 

Found  on  husks  and  in  the  juice  of  corn  before  processing.     Causes  souring  of  corn. 
Magnified  1,200  diameters. 

The  chemical  equation  for  fermentation  by  this  organism  may 
be  symbolized  as  follows ; 

CioHijoOii  +  HoO  =  4  C3H0O3 

Grape  sugar  -|-  water  =  Lactic  acid  (4  molecules). 

Glucose  =  Lactic  acid  (2  molecules). 

The  reactions  are  seldom  so  beautifully  simple,  however,  for 
there  are  liberated  by  various  germs,  gases  of  different  kinds  which 
complicate  the  chemical  equations,  and  the  quantity  of  lactic  acid 
is  of  course  less  than  the  expression  given  here.  Lactic  fermenta- 
tion, even  where  pure  cultures  are  employed,  is.  accompanied  by 
acids  of  a  volatile  nature. 

A  number  of  Pathogenic  bacteria  have  the  power  of  producing 
lacti^a^i^^Theif  grown  in  mjlk ;  among  these  might  be  mentioned 
the  Cholera  bacillus,  Bacillus  of  typhoid  fever.  Bacterium  coli  com- 
munis. Bacterium  lactis  aerogenes  and  Friedlander's  bacillus  of 
Pneumonia. 


140  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

LACTIC  PBRMBNTATION  is  utilized  commercially .. in 
creameries  to  induce  the  ^oi/r/;zo^  of  milk.  For  this  purpose  pure 
cultures  of  the  very  best  bacteria  are  obtained  frorn  the  laboratories 
and  the  cream  is  prepared  and  sown  with  these.  Formerly  the 
souring  of  cream  preparatory  to  making  butter  was  left  to  sponta^^- 
ous^action  of  the  germs  present  in  the  cream,  consequently  a j3oor 
quality  of  butter  was  frequently  turned  out,  due  to  injurious  bac- 
teria which  were  present  with  the  desired  species.  Pure  cultures 
of  lactic  germs  are  now  made  by  and  obtained  from  such  stations 
as  the  Chris  Hansen  Laboratory  of  Little  Falls,  N.  Y.,  and  the 
acid  generators  are  charged  as  follows :  Skimmed  milk  --t£L_.the 
amount  of  two  per  cent,  of  cream  to  be  soured,  is  Pasteurized  by 


I) 


/ 


\ 


V 


Plate  40.     Aromatic  Lactic  Acid  Bacilli,  Flagellated 

Photomicrograph  of  an  aromatic  lactic  acid  bacillus  found  on  putrefying  tomatoes. 
Magnified  1,000  diameters. 


subjecting  it  to  al^out  150°  F.,  wdiich  kills  many  vegetating  forms 
of  bacteria.  The  skimmed  milk  is  then  quickly  chilled,  thus  weak- 
ening the  spores  of  the  resistant  species;  then  a  pure  culture  of 
lactic  bacteria  is  sown  in  the  milk,  which  is  kept  in  a  temperature 
of  60"  F.  for  twenty-four  hours,  in  which  time  the  lactic  germs 
begin  to  vegetate  very  fast  and  gain  the  upper  hand  of  the  species 
previously  weakened  by  heat.  The  acid  generator  is  then  ready 
to  be  added  to  the  cream,  which  has  been  Pasteurized  in  the  same 
way  that  was  adopted  for  the  skimmed  milk.  In  another  day  the 
cream  will  have  turned  sour  and  is  readv  for  churning.     Butter 


OF  . 

DECOMPOSITION  CAUSED  BY  lHg^t§K!^^fe^S.  14i 

made  from  cream  thus  treated  is  very  fine  in  flavor,  and  is  purer 
and  more  wholesome  than  that  made  from  cream  which  has  soured 
spontaneously. 

Milk  is  a  fine  medium  for  the  invasion  of  Pathogenic  bacteria. 
such_a^__Tiiberciilosis,  Typhoid  and  Diphtheria,  etc.,  and  all  these 
are  destroyed  in  the  Pasteurization  should  they  happen  to  be  pres- 
jent^    '^ 

A  short  description  of  modern  butter-making  in  this  connection 
falls  under  this  head,  especially  the  consideration  of  bacteria  there- 
with associated.  Butter  is  used  extensively  in  various  specialties 
which  are  canned  and  served  in  buffet  cars,  so  the  peculiar  flavor 
of  fine  butter  should  be  known  to  guide  the  canner  in  his  selection. 

I  was  kindly  presented  with  a  culture  of  bacteria  used  in  the 
best   creameries   for   inducing   lactic   fermentation   in    Pasteurized 


Plate  41.     Aromatic  Lactic  Acid  Bacilli 

Showing  rods  and  spores.     Magnified  1,000  diameters. 

cream  by  the  Chris  Hansen  Laboratory,  and  here  give  a  photomi- 
crograph of  the  culture,  which  is  named  "Startolinef'  The  culture 
shows  the  presence  of  Saccharomyces  Pastorianus,  and  a  coccus — 
described  by  W.  Storch — which  measures  about  i/x  in  diameter. 
There  is  also  a  fission  fungus,  discovered  by  H.  W.  Conn  in  1895, 
which  is  styled  Bacillus  No.  41.  .This  is  a  non-motile  rod  about 
i.Ti^  long,  generally  single,  sometimes  united  in  pairs,  which  grows 
best  at  75^  F.  Cream  is  not  coagulated  and  very  little  acid  is 
formed  by  it. 

The  combined  influence  of  these  organisms  is  a  pure  lactic 
fermentation  set  up  by  the  cocci  and  the  fine  flavor  produced  by 
the  Conn  Bacillus  No.  41.  There  seems  to  be  a  difference  between 
the  flavor  and  the  acidffication,  which  mav  be  described  as  follows : 


142  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

The  pure ^xnditicat ion  gives  a  tine  sweet  taste  to^the  butter,  wliiie 
the  flavor  or  aroma  has  the  characteristic  gjLjvha^  is_J^^ 
"grass  flavor"  or  "June  flavor,"  so  inarked  in  country. J:)utter  made 
when  the  grass  is  green  and  tender.  The  Conn  bacillus  was  iso- 
lated by  him  from  a  sample  of  milk  he  obtained  from  South 
America,  and  it  is  employed  by  a  large  number  of  dairies  through- 
out the  world. 

Lactic  acid  bacteria  play  an  important  part  in  the  preparation 
of  the  yeast  mash  in  distilling,  vinegar-making,  and  brewing.  The 
preparation  of  the  green  malt  for  malt  vinegar  is  interesting.  The 
malt  has  many  kinds  of  bacteria  associated,  some  belonging  to 
the  butyric  acid  group.  These  are  hardy  types  and  these  form 
spores  of  great  vitality.  The  malt  is  mixed  with  Avater  and  heated 
to  about  155°   F.,  which  kills  all  vegetating  bacteria,   but  leaves 


^^i^ 


V 


Plate  42.     Micro-organisms  in  Lactic  Acid  Generator,  called  "  Startoline." 

the  Spores  of  the  undesirable  germs  uninjured,  which,  if  allowed  to 
produce  butyric  acid,  would  prevent  the  yeast  from  accomplishing 
its  part.  In  order  to  prevent  these  from  vegetating,  artificial  sotir- 
ing  is  induced  by  lactic  acid  bacteria,  which  acidity  is  antiseptic  to 
the  butyric  bacteria.  The  lactic  acid  fermentation  is  accomplished 
either  by  the  aid  of  pure  cultures  planted  in  the  mash  or  by  main- 
taining the  temperature  at  120°  F.,  which  is  about  20°  higher 
than  the  optimum  temperature  for  the  development  of  butyric  bac- 
teria. At  120°  F.,  the  lactic  acid  bacteria  flourish  well,  and  lactic 
acid  amounting  to  about  i  to  1%  per  cent,  is  formed,  which  is 
ascertained  by  standardizing  with  normal  alkali  solutions,  such  as 
sodium  hydroxid.     The  mash  is  then  heated  to  about    1^;;°    F., 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  143 

which  kills  the  lactic  acid  germs,  also  any  other  vegetated  forms, 
and  after  cooling  sown  with  pure  cultures  of  yeast,  which  set  up 
alcoholic  fermentation  without  injury  from  the  butyric  and  acetic 
acid  groups. 

The  advantage  of  using  pure  cultures  of  lactic  acid  bacteria 
is  great,  for  the  reason  that  the  spontaneous  souring  is  apt  to  mis- 
carry at  times  and  forms  of  heat-loving  bacteria  often  find  their 
way  intothe  mash  along  with  the  lactic  acid  bacteria  from  tjfie 
air. 

The  pure  culture  now  used  is  one  discovered  by  Dr.  Franz 
Lafar,  of  Vienna,   from  a  yeast  mash   in  the  Lietzen  Distillerv. 


Plate  43.     Bacillus  Acidificans  Longissimus 

Magnified  1,000  diameters. 

He  named  the  germ  Bacillus  acidificans  longissimus  from  the  fact 
that  it  is  very  much  longer  than  the  ordinary  lactic  acid  bac- 
terium. This  organism  measures  ift  in  breadth  by  from  2  to  20/x 
in  length,  and  has  the  power  of  producing  more  lactic  acid  than 
any  other  germ  so  far  discovered.  A  pvu*e  culture  was  obtained 
from  the  Berlin  Experimental  Distillery  Station  (Versuchsstation 
fur  Brennerei),  Germany,  but  was  dead  when  it  reached  us. 

By  means  of  pure  cultures  of  this  organism,  lactic  acid  may 
be  produced  at  small  cost  compared  to  the  price  jDaid  for  the  chem- 
ical preparation.  Lactic  acid  js^requirej:!  for  special  industnes, 
such  as  dyeing  and  color  printing  on  fabrics. 

Lactic  fermentation  takes  place  in  the  preparation  of  pickled 
meats,  sauerkraut,  pickles,  white  pearl  onions,  beets,  cauliflower^ 


144  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

olives  and  various  products  which  are  put  away  for  curing  in  brine^ 
Only  a  limited  amount  of  salt  is  used  at  first  because  salt  has  anti- 
septic power,  causing  plasmolysis  of  the  germ  cells.  The  lactic 
acid  group  does  not  suffer  in  the  presence  of  limited  quantities,  and 
soon  produces  lactic  acid  in  sufficient  amounts  to  prevent  the  de- 
velopment of  the  germs  peculiar  to  the  various  food  products  which 
are  pickled. 

The  brine  first  added,  ought  to  register  about  75  on  the  Beaume 
salt  scale,  and  as  fast  as  the  salt  is  absorbed  more  salt  must  be 
added  until  the  fermentation  is  completed.  At  no  time  should 
the  scale  show  less  than  50  degrees.  The  brine  will  be  found 
heavier  at  the  bottom  than  at  the  top,  so  agitation  is  necessary 
or  a  pump  may  be  used  to  lift  the  bottom  brine  up  to  the  surface. 
If  this  be  done  once  or  twice  a  day  good  results  will  be  obtained. 

This  method,  wdiile  used  extensively,  is  faulty  from  the  fact 
that  the  lactic  fermentation  is  set  up  spontaneously  by  germs  from 
the  atmosphere.  The  result  is  that  harmful  races  of  bacteria 
sometimes  gain  an  entrance  in  company  with  the  lactic  acid  germs, 
and  unpleasant  flavors  are  produced.  Soft  pickles,  slimy  cauli- 
flower and  discolored  meats,  are  due  to  the  admission  of  bacteria 
which  break  up  cellulose  and  others  belonging  to  the  chromogenic 
group  described  in  Chapter  IT.  The  bacteria  which  gain  entrance 
with  the  lactic  acid  bacteria  belong  chiefly  to  the  Subtilis  group, 
and  these  thrive  w^ell  even  in  the  presence  of  considerable  quantities 
of  salt,  and  in  the  presence  of  lactic  acid  in  limited  amounts. 

There  is  room  for  great  improvement  in  the  pickling  of  sjucli 
products  as  mentioned;  by  first  heating  the  raw  material  to  a  point 
where  all  vegetating  forms  will  be  killed — about  160°  F. — and 
chilling,  then  by  adding  the  proper  amount  of  salt  and  sowing 
a  pure  culture  of  lactic  acid  bacteria,  uniform  results  can  surely 
be  obtained. 


PRKPARATION    01^   SAU]?,RKRAUT. 

As  we  have  stated,  lactic  fermentation  plays  an  important  part 
in  the  preparation  of  sauerkraut,  the  lactic  fermentation  being  in 
fact  the  desired  chemical  change.  Let  us  therefore  look  carefully 
into  the  process  and  gather  a  few  facts  that  may  lead  to  improve- 
ment of  the  quality  and  minimize  the  losses.  After  the  cabbage  is 
cored  and  cut  it  is  put  into  large  wooden  tanks  w^ith  salt  sprinkled 
over  each  layer  and  packed  firmly.  Finally  there  is  a  top  weighted 
down,  and  according  to  present  methods  fermentation  is  permitted 
to  take  place  spontaneously.  There  are  various  spore-bearing  bac- 
teria and  lactic  acid  germs  throughout  the  whole  tank.  A  gradual 
increase  of  temperature  takes  place  and  the  various  spores  begin 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  145 

to  vegetate  in  proportion  to  tlie  amount  of  air  that  is  circulating. 
The  temperature  rises  gradually  until  it  reaches  between  iio°  and 
1 20-  F. 

At  100°  F.  the  spore-bearing  bacteria  will  gain  the  mastery 
and  as  more  weight  is  put  on  the  top  the  air  is  excluded  and  the 
temperature  reaches  abotit  120°  F.,  which  is  the  optimum  point 
for  the  lactic  germs,  and  the  activity  of  the  other  class  is  im- 
peded. At  this  temperature  the  lactic  fermentation  goes  on  until 
sufficient  acid  is  formed  to  prevent  decomposition  by  the  other 
class.  Now  the  improvement  that  suggests  itself  is  this :  Instead 
of  depending  upon  the  lactic  acid  germs  in  the  atmosphere  to  find 
entrance  to  the  cabbage,  let  a  pure  ctilture  be  sown  throughout 
the  tank  and  the  temperature  raised  at  once  to  120°  F.  Lactic 
fermentation  by  the  pure  culture  would  begin  at  once,  and  the  in- 
imical germs  would  not  be  able  to  grow,  which  would  give  uni- 
form results — a  beautiful  white  sauerkraut  with  a  delicate  aromatic 
flavor.  The  temperature  at  the  center  may  be  tested  by  pushing 
a  self-registering  thermometer  down  from  the  top.  After  having 
once  reached  the  proper  temperature,  pressure  from  the  top  can 
be  regulated  to  keep  it  uniform. 

There  is  no  branch  of  the  food  product  industry  which  suffers 
such  severe  losses  as  that  devoted  to  brining  and  pickling,  and  there 
is  great  need  of  improvement  over  present  methods  to  enable  the 
manufacturers  to  depend  on  their  processes.  The  installation  of 
the  laboratory  where  pure  cultures  of  useful  bacteria  may  be  ob- 
tained is  a  great  boon.  There  are  many  causes  of  spoilage  in  the 
salting  houses;  frequently  the  water  is  bad,  due  to  minerals  and 
injurious  bacteria;  different  crops  of  raw  material  will  vary  in  the 
number  and  character  of  bacteria  infesting  them,  and  inability  to 
get  proper  fermentation  at  all  times,  makes  the  problem  of  se- 
curing uniform  results  difficult.  No  fixed  rule  can  be  laid  down 
where  dependence  is  placed  upon  spontaneous  fermentation,  and 
the  quality  secured  depends  largely  upon  the  kill  of  the  one  wdio 
is  doing  the  work.  AVith  pure  cultures,  however,  there  is  very 
little  chance  to  have  poor  quality  if  the  material  is  good.  There 
isa  iTiarked  improvement  in  the  quality  of  goods  turned  out  in 
manyLJiid_ustri£S_jliie_tq_  tlie_titilization  of  pure  cultures  of  useful 
ba^cteria,  and  the  manjLvfacturers  of  food  products  will  also  gradual- 
ly become  interested.  ~ 

Now  let  us  condense  the  directions  governing  the  lactic  fer- 
mentation in  brining: 

FIRS7\  make  liquids  containing  pure  culture  of  lactic  acid 
bacteria  by  stirring  the  culture  into  a  quantity  of  distilled  water. 

SECOND,  sprinkle  the  liquid  over  each  layer  of  shredded 
cabbage,  also  the  required  amount  of  salt. 

V 


146  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

THIRD,  increase  the  temperature  to  120°  F.  and  maintain 
at  that  point  until  the  lactic  fermentation  starts,  then  control  the 
temperature  by  pressure  from  the  top. 

BNSILAGB. — We  have  referred  to  the  utilization  of  waste 
material,  such  as  cobs,  husks,  peelings,  strings  and  ends  of  beans, 
pea  pods,  etc.  The  quality  of  an  ensilage  made  from  these  depends 
upon  the  care  of  the  silo.  The  scientific  principles  are  nearly  the 
same  as  those  outlined  for  brining  except  that  the  salt  is  not  used. 
When  the  silo  is  filled,  pressure  is  brought  to  bear  to  bring  the 
temperature  up  to  120°  F.,  which  is  the  proper  point  favorable 
to  the  thermogenic  bacteria,  among  which  various  races  of  lactic 
bacteria  predominate.  There  are  other  varieties,  however,  which 
are  heat-loving  and  some  butyric  and  valeric  acids  are  elaborated. 
By  this  method  the  loss  of  digestible  albuminoids  is  great  and 
compounds  are  formed  which  have  no  value  in  feed  material  for 
cattle.  Ammonia  and  amide  compounds  are  formed  by  the  decom- 
position of  albuminoids. 

The  undesirable  features  of  this  method  can  be  entirely  over- 
come by  controlling  the  bacteria  which  are  useful  in  the  production 
of  good  ensilage.  A  pure  culture  of  lactic  acid  bacteria,  if  sowed_ 
in  the  silo  at  the  proper  time  and  at  the  temperature  favorable  to 
their  growth,  will  insure  a  valuable  and  marketable  product  for 
feeding  farm  stock. 

The  lactic  bacteria  are  utilized  in  the  tanning  industry  in 
the  fermentation  of  the  plumping  soak  and  the  bark  liquor,  which, 
of  course,  has  no  connection  with  the  canning  industry  and  simply 
mentioned  here  as  a  fact,  interesting  from  a  bacteriological  stand- 
point. 

Lactic  bacteria,  then,  are  useful  in  the  preparation  of  various 
food  products  and  the  transformations  accomplished  by  them  afe 
seldom  inimical,  as  the  great  majority  of  them  are  easily  destroyed 
at  ordinary  temperatures,  but  there  is  one,  possibly  two,  varieties 
which  are  associated  with  milk  and  form  spores  of  great  resisting 
power. 

PUTREFACTION. 

Putrefaction  is  a  term  usually  differentiated  from  fermenta- 
tion by  some  authors  because  the  material  which  undergoes  putre- 
factive decomposition  is  albuminous,  wdi.ile  the  carbohydrates  are 
changed  by  fermentation.  Micro-decomposition,  however,  takes 
in  putrefaction,  as  such  transformations,  w^hether  accomplished  in 
albuminous  substances  or  in  carbohydrates,  are  the  result  of  the 
vital  activity  of  bacteria;  in  fact,  the  same  germs  are  frequently 
able  to  decompose  either  substance  when  planted  under  favorable 
conditions. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  147 

FUTRBf  ACTION  is.  accompli  shed  in  substances  which  con- 
tain^carbon,  oxygen,  hydrogen,  nitrogen,  sulphur,  etc.,  while  fer- 
mentation has  been  restricted  to  substances  containing  only  carbon, 
oxygen  and  hydrogen.  The  breaking  up  of  albuminous  substances 
is  generally  accompanied  with  disagreeable  odors,  which  are  no- 
ticed in  such  elaborations  as  indol  and  skatol  where  nitrogen  and 
sulphur  are  combined.  Sulphuretted  hydrogen  and  the  foul  odor 
of  dejecta  are  due  to  the  cleavage  of  protein  matter.  Ammonia 
and  the  amines  are  the  products  of  alkaline  nature  set  free  from 
decomposing  proteins,  while  acids  often  pleasant  in  taste  and  flavor 
are  formed  by  fermentation  of  carbohydrates.  There  are,  however 
a  number  of  bacteria  which  are  peculiar  to  putrefaction  and  are 
seldom  if  ever  found  in  carbohydrates. 

The  tearing  down  processes  are  therefore  complete,  fermen- 
tation_splitting  the  carbohydrates  and  putrefaction  splitting  the  pro- 
teins into  simple  elements.  In  this  manner  all  dead  matter,  whether 
belonging  to  the  vegetable  or  animal  kingdoms,  is  reduced  to  simple 
elementary  compounds  and  is  not  permitted  to  accumulate.  Bac- 
teria frequently  cause  death  to  both  plant  and  animal  life,  but  death 
•may  result  from  climatic  changes  or  old  age,  or  through  renew- 
ing processes.  The  leaves  of  the  trees  are  touched  by  frost  and 
fall;  the  blossoms  perish  and  the  animal  sheds  his  skin  and  hair 
and  all  nature  is  constantly  putting  off  the  old  and  renewing  as 
fast  as  necessary.  Death  therefqre_is  natural  and  not  always  caused 
by  bacteria.  One  is  apt  to  fall  into  the  error  that  bacteria  are 
primarily  the  cause  of  all  dead  matter,  since  they  are  known  to 
be  responsible  for  so  many  diseases,  but  close  study  of  life  will 
t^ch  us  that  this  is  not  true.  How  wonderful  then  is  the  plan 
of  nature  for  the  removal  of  the  vast  amount  of  organic  matter 
that  is  thrown  down  all  the  time!  \Vere  it  not  for  the  bacteria 
the  earth j^vould  soon  be  unfit  for  habitatipn.and_nature  would  be 
unable  to_ furnish  the.  elements  necessary  for  removing  worn-out 
matter.  ~^  ' ' ' 

The  carbon  (in  decomposing  matter)  (combined  in  tlie  mole- 
cules) is  set  free  as  carbonic  acid  gas,  the  hydrogen  and  oxygen 
combine  and  form  water,  the  nitrogen  and  sulphur  in  the  protein 
molecule  form  nitrates  and  sulphites  and  these  elements  are  then 
in  a  simple  state  and  can  be  utilized  by  vegetable  kingdom  directly 
and  by  the  animal  kingdom  indirectly  in  building  up  new  tissue; 
the  vegetable  kingdom  using  the  carbonic  acid  gas  in  the  atmosphere 
and  the  nitrates  in  the  earth,  and  the  animal  kingdom  using  the 
starch,  fats,  sugar,  etc..  obtained  from  the  vegetable  kingdom. 
Thus  we  see  that  the  vegetable  kingdom  is. the  _S£).urce  of  nearIy_alL 
food  supply,  to  the  herbivorous  animals  directly  and  to  the  carnivor- 
ous animals  indirectly,  ^vhile  man  is  furnished  by  a  vegetable  diet 
directly  and  a  flesh  diet  indirectly  bv  the  vegetabkkingdom. 


148  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

Vibrio  Choleras  Asiaticae,  Koch  (1884) 

CHOLERA     SPIRILLUM^    COMMA    BACILLUS;    BACILLE    VIRBULE     (fR,). 

Origin. — Found  in  the  excreta  of  cholera  patients,  also  in  the  in- 
testines after  death.     Found  several  times  in  the  water  supply  and  milk. 

Form. — Short,  rather  thick  rod,  having  rounded  narrowed  ends,  and 
varying  from  a  straight  rod  to  one  bent  in  the  form  of  a  half  circle;  it 
usually  resembles  a  comma,  from  which  it  derives  its  name  of  comma  ba- 
cillus. If  two  cells  remain  attached  the  letter  "S"  is  formed.  When 
grown  in  liquid  media  under  unfavorable  conditions  it  may  form  long 
spirals.  The  bent  rod  is  a  segment  of  a  spirillum  and  is  called  a  vibrio. 
In  old  cultures  peculiar  involution   forms   develop. 

Motility. — Actively  motile,  usually  having  at  one  end  a  single  flagel- 
lum,  sometimes  two.  Flanging-drop  cultures  should  be  developed  at  37° 
— motion,  spirals  and  involutions  occur. 

Sporiilation. — So  called  Arthrospores.  No  resistant  forms  are  known. 
Not  true  spores. 

Anilin  Dyes. — It  is  stained  slowly.  Carbolic  fuchsin  stains  very  well. 
Does  not  stain  by  Gram's  method. 

Grozvth. — At  ordinary  temperature  it  is  fairl}^  rapid. 

Plates. — On  gelatin  plates  kept  at  22°,  white  or  pale-yellow  colonies, 
coarsely  granular,  with  irregular  rough  border  which  is  surroundel  by  a 
faint  rosy  hue,  are  formed.  These  colonies  at  first  appear  as  small,  white 
points ;  these  gradually  reach  out  to  the  surface,  producing  rather  slow 
liquefaction,  so  that  funnel-shaped  depressions  are  formed.  The  colonies 
develop  in  fifteen  to  twenty  hours.  Entire  liquefaction  of  gelatin  occurs 
after  several  days.  On  agar  plates  at  37°,  the  large  colonies  present  a 
peculiar,  bright,  grayish-brown  appearance  which  is  quite  distinct  from 
that  of  the  common  bacteria  found  in  water  and  in  feces. 

Stab  Culture. — In  gelatin  growth  occurs  along  the  entire  line  of  in- 
oculation. A  funnel-shaped  liquefaction  with  an  air  space  above  forms  at 
the  surface,  the  growth  subsiding  to  the  lower  part.  The  lower  part  of 
the  puncture  is  gradually  widened  by  liquefaction;  the  growth  settles  to 
the  bottom,  and  the  entire  contents  of  the  tube  are  eventually  liquefied. 

Streak  Culture. — On  agar,  a  glistening,  whitish  growth  is  formed. 
It  liquefies  blood-serum  slowly.  On  potato,  kept  in  the  incubator,  a  thin, 
grayish  or  yellowish-brown,  somewhat  transparent  layer  is  formed.  This 
resembles  that  of  the  glanders  bacillus  to  some  extent.  Unless  a  mixed 
culture  is  used  no  growth  is  obtained  at  ordinary  temperature. 

Bouillon. — Rapid  growth,  especially  in  incubator,  and  a  scum  or  pelli- 
cle is  formed  on  the  surface.  Cultures  twelve  to  twenty-four  hours  old 
display  a  reddish-violet  color  on  the  addition  of  sulphuric  acid— the  indol 
reaction — due  to  the  formation  of  indol  and  nitrous  acid. 

Milk. — In  sterile  milk  the  growth  is  abimdant,  without  much  change; 
also  in  sterile  water. 

Oxygen  Requirements. — Artificial  cultures  require  oxygen. 

Temperature. — Grows  best  at  37°  C.  Will  grow  at  i5°-42°  C.  Killed 
at  50°  C.   _ 

Behavior   to    Gelatin. — Liquefies    slowly ;    old   cultures,    especially. 

Immunity. — Subcutaneous  or  intra-peritoncal  injections  of  the  dead 
or  living  vibrio  yield  a  serum  which  is  anti-infectious;  injections  of  the 
soluble  toxin  yield  an  antitoxic  serum.  The  cell  contents  of  the  cholera 
vibrios  render  immune.  Pfeifi'ers  reaction  with  the  serum  of  convalescents 
or  that  of  immunized  animals  or  man   (Chap.  XIV). 

Pathogenesis. — Rabbits  are  killed  very  quickly  by  intravenous  injec- 
tions. In  guinea-pigs  intra-duodenal  injections  or  introduction  of  cul- 
tures into  the  stomach,  previously  alkalized,  produce  death  with  choleraic 
effects.  The  intraperitoneal  injection  of  agar  culture  is  fatal  in  the  ex- 
treme to  guinea-pigs;  is  attended  with  rapid  fall  of  temperature.  Sub- 
cutaneous injections  of  pigeons  is  not  fatal.  Typical  cholera  is  pro- 
duced in  man  by  ingestion  of  cultures.  The  feeding  of  cultures  to  new- 
born rabbits  and  guinea  pigs  is  usually  attended  with  fatal  results. 

Infection. — Takes  place  along  the  alimentary  canal,  through  water, 
food,  contact  with  freshly  soiled  matter,  etc.  The  bacillus  grows  in  the 
intestines,  and  characteristic  symptoms  of  intoxication  are  induced  by  the 
soluble  poisons  elaborated  by  it. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS. 


149 


Putrid  substances  contain  carbon  and  nitrogen  in  composi- 
tion and  the  plants  are  unable  to  use  them  thus  combined,  so  the 
putrefactive  bacteria  set  in  to  decompose  these  combinations  and 
the  carbon  is  soon  set  free  as  carbonic  acid  gas,  and  the  nitrates 
and  nitrites  find  their  way  into  the  soil  as  ammonia,  and  this  is 
utilized  by  plant  life. 

The  putrefactive  bacteria  are  called  saprogenic,  and  by  the 
old  writers  the  bacterium  termo,  which  is  not  a  name  signifying 
an  individual  species,  but  a  class  to  which  many  allied  species  be- 
long. The  saprogenic  bacteria  may  have  the  power  to  set  up  true 
fermentation  when  planted  in  substances  containing  sugar,  starch, 
etc.,  but  their  true  character  is  asserted  in  their  ability  to  decom- 
pose albuminoid  substances. 


I 


Z' 


Plate  44 


smelling  gases. 


The  decomposition  of  albumen  is  generally  attended  with  bad- 
Some  of  these  gases  are  so  foul  that  the  bacteria 
which  produce  them  are  hard  to  handle.  The  odor  elaborated  by 
one,  called  Proteus  Vulgaris,  is  abominable. 

The  compounds  which  have  such  malodorous  characteristics 
belong  to  the  aromatic  class.  Several  of  them  have  been  isolated 
by  L.  Brieger,  M.  Von  Nencki,  and  E.  Bauman. 

Indol  C^H-N  is  produced  by  quite  a  number  of  bacteria,  and 
its  presence  forms  a  basis  of  differentiation  of  closely  allied  species. 


160  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

It  combines  with  nitrous  acid  as  an  imide  to  produce  nitrose  indol, 
which  is  red  in  color.  This  characteristic  is  brought  out  by  adding 
Sulphuric  Acid  H0SO4  in  the  test.  The  Cholera  Spirillum  was 
the  first  pathogenic  organism  discovered  which  produced  indol. 

Skatol  was  isolated  by  Brieger  in  1877  i^^  human  excreta,  its 
presence  being  attributed  to  bacteria  in  the  intestines;  it  is  a  very 
foul  substance. 

Sometimes,  Phenol  is  a  product  of  vital  activity  resulting 
from  the  decomposition  of  albuminoid  substances ;  also  Orthocresol 
and  Paraocresol. 

Methyl  indol  acetic  acid  is  a  very  foul  substance  associated 
with  degredatioa  of  albuminoids.  It  was  isolated  by  N.  Von 
Nencki  from  a  culture  of  Bacillus  liquefaciens  magnus,  growing 
in  the  anaerobic  state. 

Putrefaction  is  a  common  (phenomenon)  in  (imperfectly  steri- 
lized) canned  goods  of  certain  kinds,  principally  cans  containing 
;  meats,  meat  extracts,  vegetables  containing  albumen,  and  milk. 
|,This  may  be  due  to  leaky  cans  or  insufficient  sterilization.  The 
;[  odors  from  swelled  cans  of  corn,  peas,  beans  and  all  kinds  of  meat 
■i  are  familiar  to  very  canner  of  those  products. 

The  greatest  possible  care  in  the  packing  of  these  goods  is 
essential.  In  the  process  of  putrefaction  there  are  various  pto- 
\  maines  and  toxic  poisons  formed,  which  sometimes  cause  consider- 
5  able  trouble.  Whenever  a  case  of  poisoning  occurs  which  the 
physician  attributes  to  canned  goods,  the  packer  suffers  to  some 
extent,  but  the  whole  industry  suffers  more.  Packers  sometimes 
get  very  poor  advice  from  incompetent  writers  and  the  following  is 
a  sample. 

REPROCESSED   TWEAKS. 

The  following  quotations  are  made  from  an  article  which  ap- 
peared in  one  of  the  canners'  journals  in  a  series  of  articles  pub- 
lished for  the  benefit  of  packers : 

"The  first  paragraph  is  headed  'Defective  Cans,'  and  reads : 
'While  piling  out,  some  defective  cans  may  be  detected;  these 
should  have  immediate  attention.  Open  tip  holes,  repair  cans,  then 
retip  and  reprocess  regular  time.  In  some  instances  these  may 
again  be  placed  in  the  same  grade  of  goods.  When  leaks  are  found 
after  goods  have  stood  several  days,  open  tip  hole,  repair  can,  ex- 
haust, tip  and  process  regular  time.  Goods  thus  treated  may  be 
classed  in  a  lower  grade.'  " 

Such  advice,  scattered  broadcast,  is  extremely  dangerous. 
There  is  probably  nothing  outside  of  deliberateTy  putting  poTson 
into  food  that  would  cause  such  dangerous  stomach  and  intestinal 
complications  as  this  practice. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  151 

In  order  that  the  packers  may  more  fully  understand  the 
danger  of  putting  out  reprocessed  leaks,  let  us  look  into  the  subject 
from  various  points  of  view. 

1.  There  is  danger  of  ptomaines  forming  in  putrescible  food. 

2.  There  is  danger  of  pathogenic  molds  and  yeasts  gaining 
entrance  to  acid  foods. 

3.  There  is  danger  of  tin  and  lead  poison. 

4.  The  quality  is  extremely  poor,  therefore  detrimental  to 
the  packers'  reptitation. 

The  first  reason  for  not  selling  such  goods  is  the  danger  of 
ptomaines  having  formed  in  putrescible  material. 

There  are  a  number  of  bacteria  freely  distributed  in  the  air, 
water  and  decomposing  matter,  which  are  capable  of  setting  up 
putrefactive  processes.  These  bacteria  will  not,  as  a  rule,  grow 
readily  on  raw  material,  but  thrive  luxuriantly  on  a  great  vanety 
of  cooked  foods.  Owing  to  their  wide  distribution  in  nature,  physi- 
ciahs  andT^ome  scientists  have  not  taken  true  account  of  them,  and 
their  power  to  produce  ptomaines.  A  ptomaine  is  a  complex  chem- 
ical compound  formed  in  several  ways,  principally  as  a  product 
elaborated  by  certain  bacteria  belonging  to^  the  putrefactive  class, 
ancFalso  to  tLe  pathogenic  bacteria  (which  are  the  cause  of  diseases 
m  man  and  animals  and  are  parasitic  on  living  protoplasm). 

Not  all  ptomaines  are  poisons;  only  a  few  of  them  are  so 
classed,  but  these  few  are  either  formed  or  excreted  by  a  large 
num^ber  of  bacteria.  The  poisons  elaborated  by  the  pathogenic  bac- 
teria are  toxins  which  may  be  united  with  various  other  substances, 
and  these  are  termed  ptomaines;  the  real  poison,  however,  is  a 
toxin.  Such  bacteria  as  typhoid,  tetanus," glanders,  cholera,  etc., 
ail  produce  toxins,  and  these  toxins  unite  with  other  compounds 
which  may  be  extracted  with  ether  and  thrown  down  as  ptomaines. 
The  ptomaines  commonly  found  in  decomposing  vegetables,  meats, 
fish,  cheese,  milk,  etc.,  are  generally  due  to  the  more  common  and 
widely  distributed  organisms  shown  in  the  plates.  There  are  also 
other  varieties  generally  regarded  as  quite  harmless  which  form 
ptomaines  in  very  many  different  kinds  of  food,  especially  when 
forced  to  grow  in  an  anaerobic  condition,  that  is,  where  air  is  ex- 
cluded. In  the  ordinary  tin  can  this  condition  is  very  nearly  com- 
plete, especially  after  fermentation  has  set  in  and  carbonic  acid  gas 
or  phosphuretted  hydrogen  has  driven  out  the  oxygen  through  a 
small  leak.  In  such  a  condition  the  ptomaine  bacteria  are  forced 
to  obtain  that  very  necessary  element — oxygen — from  molecules 
with  which  it  is  combined.  The' breaking  down  processes  are  there- 
fore quite  rapid  and  the  chemical  changes  take  place  within  very 
limited  time,  so  that  canned  goods  could  thus  be  changed  within 
forty-eight  hours,  or  perhaps  less. 


152  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

Ptomaine  poisoning  is  much  more  common  than  generally 
known.  The  evil  effects  are  often  experienced  after  meals,  when 
cramps  are  followed  by  diarrhoea  and  severe  headache.  Sometimes 
these  cases  are  quite  severe,  and  the  unfortunate  suffer  terrible 
pains  with  tremors,  followed  by  coma,  and  even  death.  The  cases 
on  record  are  not  a  few,  where  whole  companies  of  individuals 
have  been  stricken  after  banquets,  suppers,  picnics,  parties,  etc. 
Some  of  these  cases  have  been  thoroughly  investigated,  and  the 
ptomaine  responsible  has  been  obtained  from  cultures  of  the  bacteria 
found  in  the  food.  Usually  in  such  cases  the  food  does  not,  by 
any  peculiar  taste  or  odor,  indicate  the  presence  of  an  injurious 
substance.  As  we  have  previously  stated,  the  chemical  changes  are 
rapid  and  the  potmaines  may  be  formed  where  iinperceived  decom- 
position is  taking  place.  It  usually  happens  that  food  containing 
ptomaines  has  been  exposed,  or  worked  over,  and  the  task  of  defin- 
ing the  cause  of  such  poisoning  is  often  quite  difficult. 

I  could  mention  a  number  of  cases  from  all  parts  of  this  coun- 
try and  Europe,  where  families  have  been  stricken  and  the  poison- 
ing was  charged  directly  against  canned  goods  by  the  attending 
physicians.  In  my  writings  on  ptomaines,  I  ha^'e  scored  such  de- 
cisions by  physicians  mercilessly,  because  I  iirmly  believe  that  many 
of  them  jump  at  conclusions  without  proper  investigation.  Now 
permit  me  to  say,  if  the  packers  should  follow  such  advice  as  ap- 
pears in  the  quotation  in  the  beginning  of  this  paper,  no  one  with 
any  respect  for  his  integrity  would  dare  to  make  defense  against 
the  charge  that  ptomaine  poisoning  is  due  to  canned  goods.  Any 
physician  who  should  happen  to  read  that  packers  worked  into 
salable  packages  goods  undergoing  decomposition  would,  without 
the  least  hesitation,  cast  the  blame  of  such  poisoning  directly  on 
canned  goods,  if  any  had  been  eaten  by  the  unfortunate  persons. 
In  our  laboratory  work  we  have  isolated  from  spoiled  goods  of 
many  different  kinds,  various  bacteria  classed  as  common,  some 
of  them  harmless  to  man  when  taken  into  the  stomach,  yet  these 
very  bacteria  will  produce  ptomaines  and  toxins,  especially  when 
growing  with  other  varieties.  Even  Bacillus  Prodigiosus,  the  com- 
mon bacterium  which  produces  a  red  color  on  potatoes,  bread,  etc., 
a  bacterium  found  commonly  in  the  air,  soil,  water,  decomposing 
material,  and  on  the  leaves,  pods,  vines  and  stalks  of  vegetation, 
will  produce  metabolic  compounds  vrhen  growing  with  other  or- 
ganisms, and  these  compounds  have  known  toxic  properties,  fatal 
in  some  cases  to  animals,  by  subcutaneous  and  intraperitoneal  in- 
jections. Bacillus  subtilis  and  bacillus  allii.  the  former  a  very 
widely  distributed  organism,  the  latter  a  bacterium  found  on  de- 
composing onions,  give  rise  to  poisonous  compounds  in  some  cases. 
We  have  recently  isolated  a  bacillus  from  a  leaky  can  of  mince 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS. 


153 


W     . 


(^       % 


Plate  45.     Ptomaine  Bacillus  from  Mincemeat,  showing  Flagella 

PhotomicroKraph  of  a  bacillus  found  in  perforated  can  of  mince  meat.  This  organism  produces  a 
ptomaine.  The  growth  is  similar  to  proteus  vulgaris.  It  is  endowed  with  numerous  flagella,  which  are  the 
organs  of  locomotion.  It  is  actively  motile.  Isolated,  stained  by  special  method,  mounted  in  xylol  balsam,  and 
photographed  through  the  microscope.  Magnified  with  1-12  homogenous  oil  immersion  lens  and  illuminated  with 
acetylene  radiant.     Magnified  1,200  diameters. 


Plate  46.     Ptomaine  Bacillus  from  Mincemeat 

Showing  rods  and  spores.     Magnified  1,200  diameters. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  155 

meat,  which  produces  choHn,  gadinin  and  trimethylamin,  well 
known  ptomaines.  This  mince  meat  was  canned  and  a  pie  made 
with  it  made  one  person  very  sick,  causing  cramps,  cold  extremities 
and  tremors. 

I.  Proteus  Vulgaris,  Mirabilis  and  Zenkeri  and  the  colon  bac- 
illus are  found  throughout  the  alimentary  tract  in  man  and  many 
animals,  also  on  cooked  foods  undergoing  decomposition.  They  are, 
therefore,  quite  common,  but  when  permitted  to  grow  in  food  will 
produce  powerful  ptomaines. 

How  isit,  then,  thatjwe_are^  not  more  frequently  poisoned,  if 
these^are  socommoia?  Of  the  varieties  mentioned  one  or  rnbre  are 
taken  into  the  stomach  with  various  foods  at  every  meal.  We  aim 
to  eat_Qnly  Jresh  Jpod^jwhich  passes  into  the  stomach  where  it  is 
acted  upon  by  the^  digestiyc_enz3niies»_o^stric  Jujxie^  saHva  and  bile. 
These  substances  retard'  the  development  of  these  bacteria  and  de- 
stroy them  in  some  cases.  The  food  passes  on  to  the  intestines, 
where_theacrds  are  neutralized  and  the  Jood  is  rendered  alkaline. 
Here,  then^is  a  favorable  environment  of  temperature  and  alkalin- 
ity so  ^reat  numbers  of  bacteria  grow  rapidly,  only  to  be  cast  out 
usually  before  any  poisons  are  absorbed. 

AVe  can  therefore  readily  see  the  difference  between  a  partial- ' 
ly  decomposed  food  (containing  these  bacteria  and  their  poisons)  \ 
taken  into  the  stomach,  and  perfectly  fresh  food,  or  food  that  has ' 
been  kept  free  from  the  action  of  bacteria. 

From  this  it  is  quite  reasonable  to  suppose  that  some  of  the 
bacteria  which  form  ptomaines  will  gain  access  to  leaky  cans  and 
will  form  these  poisons  rapidly.  I  want  to  say  here  that  after  the 
ptomaines  are  formed  they  are  not  always  driven  out  by  cooking, 
in  fact  some  of  the  most  deadly  ptomaines  are  active  after  cooking. 
The  bacteria  may  all  be  destroyed,  but  their  poison  remains. 

•    2.     There  is  danger  of  pathogenic  molds  and  yeasts  gaining 
entrance  to  acid  foods. 

There  are  several  molds  that  have  been  classed  as  pathogenic ; 
prominently,  Aspergillus  niger  and  Aspergillus  fumigatus.  Molds 
grow  well  on  acid  fruits  and  vegetables  and  the  products  formed, 
wh]le__  not  considered  deadly,  might  cause  stomach  and  intestinal 
troubles.  Several  yeasts  have  been  found  which,  when  putrid,  yield 
metabolic  compounds  of  a  basic  nature,  belonging  to  the  amine 
group  of  ptomaines.     (See  Vaughn  &  Novy's  "Cellular  Toxins.") 

3.     There  is  danger  of  tin  and  lead  poisoning. 

It  is  a  well  known  fact  that  tin  and  lead  compotmds  are 
pojsonous.  Ordinarily,  m  "canned  goods,  these  are  present  in  such 
small  quantities  that  they  are  considered  harmless.  Several  years 
ago  the  Bureau  of  Chemistry,  Department  of  Agriculture,  at  Wash- 
ington, gave  this  subject  considerable  attention.     Some  of  the  tin 


156  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


Aspero-illus  Niger,  Van  Tieghciu 

Origin. — In  putrid  substances,  in  the  lungs  of  birds,  and  acid  foods. 

Color. — Dark  brown  or  black. 

Mycelium. — Low  and  at  first  white,  afterwards  brownish  or  black. 

Fruit-Organs: — The  fruit  hyphae  are  spherical,  or  flask — or  club- 
shaped  at  the  end  which  is  covered  with  minute  bottle-shaped  bodies,  ra- 
dially arranged — the  intermediate  spore-bearers  or  sterigmae — from  which 
extend  rows  of  spores.  These  sterigmae  are  divided.  The  spores  are 
brownish  or  black  and  spherical ;  are  3-5  /x  in  diameter. 

Grozvth. — Slow. 

Bread  Flasks. — A  low  growth  is  formed  which  becomes  very  black. 

Temperature. — ^^Grows  best  at  about  35°  C. 

Pathogenesis. — It  gives  rise  to  various  ferments,  diastatic,  inverting, 
and  others.  The  intravenous  injection  of  spores  in  rabbits  is  not  followed 
by  as   malignant   results   as    with   Aspergillus    fumigatus. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  157 

plate  examined  at  that  time  gave  unfavorable  results,  but  in  gen- 
eral there  were  found  only  small  quantities  of  the  oxids  of  tin  and 
lead. 

AA'hen  decomposition  sets  in,  however,  there  are  formed  acids' 
whicli  attack  tin  plate  and  the  lead  in  the  solder  most  vigorously, 
and  the  gases  throw  them  down  in  the  form  of  insoluble  oxids, 
which  are  poisonous.  Canned  goods  which  become  swelled  be- 
cause of  leaks  have  formed  considerable  acid  and  gas  by  the  ac- 
tion of  bacteria  and  when  worked  over  must  contain  tin  and  lead 
in  appreciable  amounts. 

4.     The  quality  is  extremely  poor,,  therefore  detrimental  to 
the  packer's  reputation. 


Plate  47.     Aspergillus  Niger 

Photomicrograph  of  unstained  mold  Aspergillus  Niger,  which  is  often  seen  on  food  products,  which  it 
causes  to  ferment.  It  is  pathogenic,  producing  substances  deleterious  to  health.  There  are  two  large  fruit  pods 
shown.  These  are  full  of  ripe  black  spores  as  conidia.  Just  below  is  one  of  the  black  threads  of  the  mycelium. 
Magnified  600  diameters. 

From  all  that  we  have  written  it  must  follow  that  goods  sent 
out_wi];li  siich  compounds  formed  in  them  will  be  very  poor  in 
equality:  a  second  process  would  greatly  injure  the  flavor  in  perfect- 
ly pure  goods,  but  when  poisonous  compounds  are  also  present  one 
cannot  imagine  anything  more  detrimental  both  to  the  packer  and 
the  consumer.  The  evil  results  do  not  end  here;  the  whole  cannings 
industry  is  assailed  and  maligned  by  the  newspapers  and  hostile 
writers,  and  the  innocent  are  made  to  suffer  with  the  guilty. 

Every  can  of  goods  you  send  out  will  probably  reach  a  con- 
sumer who  is  looking  for  something  good  to  eat;  every  package 
will  either  make  a  friend  or  an  enemy  for  your  brand,  and  when 


158 


CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


you  are  packing  your  goods  think  of  this  all  the  time.  If  you  have 
any  cans  which  have  suffered  by  accident  in  breakdowns  of  ma- 
chinery or  foreign  matter  having  gained  entrance,  throw  them 
away  rather  than  run  any  risk  of  sending  out  goods  of  inferior 
quality. 


Plate  48 


What  disposition  can  be  made  of  leaks,  you  ask?  Cut  them 
open,  empty  them  and  send  the  contents  to  the  dump  or  wash 
them  away  in  the  sewer.  However  wasteful  this  may  seem — do  it 
— you  will  save  more  in  reputation  than  yotLcan  ever_galn  by  sell- 
ing inferior  and  dangerous  goods. 

There  should  not  be  many  leaks  if  there  is  a  proper  system  of 
inspection.  I  find  that  out  of  a  pack  of  over  ten  million  cans  one, 
year  I  lost  by  leaks  less  than  one-fifth  of  one  per  cent.,  oii_^t\yg_p.ut 
of  one  thousand.  It  is  a  good  plan  to  have  two  inspectors,  and 
\vomen  are,  as  a  rule,  quicker  to  see  a  leak  than  men.  One  of  the 
inspectors  is  placed  at  a  point  as  near  the  automatic  capper  as 
possible.  As  the  cans  pass  this  point  all  cap  leaks,  pin  hole  leaks, 
etc.,  are  taken  off  the  conveyor  and  patched.     The  other  inspector 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  159 

is  placed  at  a  point  beyond  the  tippers  and  all  tip  leaks,  buttons  and 
cans  with  suspicious  patching  are  sent  back  to  the  tippers. 

The  cans  are  conveyed  into  a  tub  of  water  where  women 
gather  and  pile  them  top  up,  into  process  crates ;  and  these  women 
are  trained  to  look  for  leaks  as  they  handle  the  cans.  A  small 
premium  for  leaks  found  at  this  point  is  a  good  incentive  for  watch- 
fulness and  the  cost  can  be  made  to  fall  on  the  inspectors  and  the 
tippers,  according  to  plans  carefully  made.  One  man  to  patch, 
two  tippers,  two  inspectors  and  four  women  to  pile  cans  in  crates 
will  be  sufficient  help  to  properly  care  for  50,000  cans  daily,  and 
the  leaks  found  in  cans,  imperfect  tin  and  caps  will  not  exceed,  as 
I  have  said,  more  than  two  out  of  one  thousand.  ' 

I  stated  previously  that  leaks  should  be  cut  open  and  the  con- 
tents emptied.    This  should  be  done  rather  than  to  haul  the  swelled 


Plate  49 

Photograph  of  a  can  of  tomatoes  packed  in  1884.  This  can  is  about  the  same  diameter  as  a  No.  2  can, 
but  taller.  The  tomatoes  after  twenty  years  are  in  fine  condition,  just  as  nice  as  freshly  canned  stock.  No 
"dating  laws"   required  here. 

cans  to  the  dump.  Strange  as  it  may  seem,  in  the  large  centers 
we  find  poor  people  who  will  take  swelled  canned  goods  home  and 
eat  them.  In  order  to  avoid  any  serious  results  it  is  better  to  dump 
the^  contents.  Of  course  some  packers,  may  say  that  the  poor  should 
not  do  this^but  in  ignorance  it  is  done,  and  the  suggestion  offered 
is^Yprthy  qFconsideration. 


160  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

There  are  always  a  number  of  persons  ready  to  take  it  up  and 
rush  into  prominence  with  such  bills  as  "Canned  Goods  Dating 
Bill"  to  correct  the  reported  evils.  There  never  was  anything 
more  absurd  than  a  dating  bill  for  canned  goods,  but  should  a 
ptomaine  be  present  by  any  possible  chance,  a  date  on  the  can 
w^ould  not  warn  the  consumer. 


AGE  DOES   NOT   AEEECT   CANNED   GOODS. 

From  Canner,  March  2,  1905. 

Plate  49  shows  a  can  of  tomatoes  which  was  put  up 
in  1884.  The  tomatoes  are  as  good  as  the  day  they  were  canned. 
While  the  exterior  of  this  can  was  very  much  rusted,  the  inside 
coating  was  perfect  and  was  no  doubt  a  very  superior  grade  of 
tin  plate.  Age  does  not  affect  canned  goods  unless  a  perforation 
should  happen  to  be  made  in  the  tin.  So  long  as  the  air  is  kept 
away,  the  contents  will  remain  in  an  unfermented  condition. 

From  time  to  time  there  have  been  rumors  of  laws  to  de- 
clare the  date  of  the  pack  on  tin  cans  in  various  states,  the  idea 
being  to  limit  the  sale  of  canned  goods  to  the  year  immediately 
following  the  pack.  This  would  be  very  unjust  because,  as  we 
say,  canned  goods  are  unaffected  so  long  as  the  container  prevents 
the  germs  from  the  air  from  gaining  entrance.  We  have  opened 
canned  goods  of  various  ages,  ranging  from  five  to  twenty  years, 
and  have  found  that  in  every  case  where  the  tin  was  not  per- 
forated, the  contents  were  perfectly  good  and  tasted  as  well  as 
the  freshly  canned  product.  American  canned  goods  are  the  best 
and  most  wholesome  food  in  the  world. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  161 


CHAPTER  V. 

Decomposition  Caused  by  Micro-organisms 
(Continued) 

Putrefaction,  Bacteria  of.     Ptomaines  and  Toxins,  Pathogenic 
Bacteria  and  Their  Action  on  Foods. 


INTRODUCTION. 


The  study  of  putrefactive  processes  and  the  bacteria  asso- 
ciated therewith  leads  up  to  the  products  elaborated  by  these 
groups.  There  are  various  products  which  are  formed  during  the 
growth  and  multiplication  of  these  bacteria,  but  the  most  important 
ones  are  ptomaines  and  toxins.  These  substances  are  not  formed 
in  canned  goods  unless  there  are  leaks  or  they  are  imperfectly  steri- 
lized, "although  it  has  been  charged  against  them  quite  frequently.  In 
order  to  understand  the  nature  of  these  substances  and  the  bacteria 
which  produce  them,  I  have  thought  it  advisable  to  describe  the 
well  known  species. 

The  general  character  of  contaminated  raw  material  is  care- 
fully described,  so  that  the  manufacturer  may  be  continually  on 
his  guard.  A  fair  understanding  of  the  subject  may  reduce  to  a 
minimum  the  chance  of  ptomaine  poisons  forming  in  manufactured 
foods  of  all  kinds.  The  study  of  this  subject  will  be  interesting 
to  the  food  chemist  as  well. 


PUTREI^ACTION. 


Sulphuretted  hydrogen  (H2S)  is  a  foul  gas  usually  present 
during  putrefactive  processes.  It  has  the  sickening  odor  of  rotten 
eggs  and  is  produced  by  a  long  list  of  bacteria.  Albuminoid  sub- 
stances are  rich  in  sulphur  compoimds  and  the  sulphur  is  easily 
liberated  and  combines  with  nascent  hydrogen  to  form  the  gas. 
Bacteria  cannot  form  this  gas  where  sulphur  is  not  present,  which 
accounts  for  its  absence  where  well  known  putrefactive  bacteria 
are  cultivated  in  certain  nutrient  media.  The  putrefactive  bacteria 
use  considerable  sulphur  in  building  up  the  protoplasm  of  their 
cells  and  the  gas  is  formed  only  in  small  quantities  in  some  cases. 


162  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

Sulphur  combines  with  ammonia  and  in  some  cases_the_  gas Js^ not 
hberated  in  sufficient  quantities  to  be  easily  detected.  This  is  in- 
teresting  in  connection  with  the  production  of  jDtornaineSi_aj_iL 
shows  that  unperceived  decomposition  may  take  place  in  albumi- 
noid substances  and  poison  may  be  produced  by  bacteria  in  suffi;; 
clent  amounts  to  cause  severe  sickness,  and  even  death,  there  being 
little  or  no  evidence  of  any  decomposition.  The  ordinary  person 
depends  largely  upon  his  sense  of  smell  to  determine  the  decom- 
position of  such  foods  as  meat,  fish,  milk,  cheese,  etc.,  but  it  is 
generally  the  case  where  there  is  no  perceptible  decomposition  that 
deceives  because  ver}^  few  persons  would  eat  any  food  that  had  a 
suggestion  of  putrefaction.  The  custom  in  some  countries ^  jDer^ 
mitting  meats  to  age  in  order  to  soften  the  fiber  must  not  be_con- 
founded  with  putrefaction. 


Plate  50.     Proteus  Sulphurans 

Photomicrograph  of  proteus  sulphurans,  a  putrefactive  organism  which  was  isolated  from  decaying  had- 
dock. It  forms  great  quantities  of  sulphuretted  hydrogen.  In  all  culture  media  the  odor  is  abominable.  It  is 
actively  motile  and  bores  into  the  deepest  layers  of  decomposing  flesh.  It  has  a  wonderful  array  of  flagella. 
Stained  by  our  own  special  method  and  mounted  in  xylol  balsam.     Magnified  1,200  diameters. 

Sulphuretted  hydrogen  is  not  easily  perceived  in  the_jdecom- 
position  of  albuminoid  substances  where  nitrates  are  present,  _as 
these  are  reduced  by  the  hydrogen  to  nitrites,  both  by  aerobic  and 
anaerobic  bacteria.  The  presence  of  this  gas  is  easily  demonstrated 
in  cultures  of  putrefactive  bacteria  by  a  simple  and  beautiful  chem- 
ical reaction.  Gelatin  plates  are  colored  Madeira  yellow  with 
(sodium  ferri-tartrate  0.5  gram,  water  50  c.c.  and  carbonate  of 
soda  added  until  alkaline)  ;  this  combines  with  the  sulphur  and 
forms  ferrous  sulphate  and  a  black  halo  or  ring  may  be  seen  around 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  163 

each  colony  of  bacteria  which  produce  snlphnretted  hydrogen.  It 
may  be  stated  here  that  peptone  added  to  the  gelatin  insures  a 
more  liberal  production  of  the  gas. 

Nearly  ah  j)athogenic  bacteria  (bacteria  which  causes  diseases 
of  man  and  animals),  form  this  gas;  the  typhoid  bacillus  produces 
sufficient  quantities  to  be  detected  in  a  close  room. 

The  bacillus  which  causes  swine  erysipelas  produces  more  gas 
than  any  other  I  have  met ;  a  bouillon  culture  resembles  yeast  fer- 
mentation in  the  amount  of  gas  bubbles  liberated. 

It  must  not  be  supposed  that  sulphuretted  hydrogen  is  the 
only  gas  associated  with  putrefaction;  there  are  various  others; 
buFTts  absence  must  not  be  taken  as  a  guarantee  that  there  is^  no 
putrefaction. 

Putrefactive  processes  occur  in  the  intestines  of  man,  .animals ' 
and  birds.  In  man  the  large  intestine  is  where  this  phenomenon  j 
takes  place,  and  while  putrefactive  bacteria  are  not  necessary,  they 
find  their  way  to  that  location,  being  introduced  with  food  and 
water.  The  principal  species  is  the  Bacillus  coli  communis  or 
Colon  Bacillus,  which  resemble  the  Bacillus  typhi  abdominalis  to 
such  remarkable  exactness  that  differentiation  is  difficult.  The  un- 
digested albuminoids  are  attacked  by  this  and  other  commonjputre- 
factive  bacteria  and  those  foul  products  known  as  indol,__skatQl, 
tyrosine,  leucine,  valeric  acid,  etc.,  are  formed.  .  Various  poisons 
are  formed  also,  but  usually  pass  away  without  causing  any  danger- 
ous complications. 

There  are  a  number  of  bacteria  associated  with  putrefaction 
which  produce  ptomaines  and  toxic  poisons  inordinary  articles  of 
food^uch  as  meat,  eggs,  milk,  ice  cream,  fish,  cheese,  etc^,_many 
oT\vhich  have  been  isolated  and  their  poisonous  products  have  been 
separated.  It  must  not  be  supposed  that  all  putrefactive  bacteria 
produce  these  poisons.  Tliey  all  produce  enzymes  of  various  kinds; 
some  are  poisons,  while  others  are  quite  harmless.  There  are  some 
ptomaines  also  which  are  not  poisons,  and  to  speak  of  all  ptomaines 
as  such,  is  a  mistake  which  has  only  recently  been  cleared  up.  Put- 
rescine  and  Cadaver ine  are  two  which  were  formerly  considered  as 
poisons,  but  recent  investigation  has  proved  the  opposite. 

Some  of  the  pathogenic  bacteria  produce  ptomaines  wdiich  act  as 
gowerf-uLpimQns;  many  of  the  toxins  have  been  separated  and  in- 
vestigators are  w^orking  to  obtain  these  principles  from  all  disease- 
producing  bacteria.  Some  diseases  formerly  thought  to  be  incurable 
have  been  successfully  treated  w^ith  the  specific  toxins  of  the  bac- 
teria which  cause  them.  Among  these  might  be  mentioned,  the 
anti-toxin  obtained  from  cultures  of  Diphtheria  Bacilli,  which  effects 
wonderful  cures  of  diphtheria,  and  recently  the  tetano-toxin  ob- 
tained from  cultures  of  Tetanus  Bacilli  has  effected  cures  of  lock- 


164  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

jaw  when  all  hope  of  recovery  by  other  means  had  been  given  up. 
These  toxins,  however,  are  not  used  in  the  pure  state^  which  w^lLd 
prove  fatal,  but  are  attenuated  by  inoculating  animals  from  which 
the  weakened  toxin  is  obtained  in  the  serum. 

Pathogenic  bacteria^  will  jDrodu€ej)oispns  on  nutrient  substances 
whicli..haye  no  albumen  in  ^their_conipasiti^>n4— these  poisons  are 
formed  synthetically.  These  poisons  have  been  named  active  al- 
buminoids by  the  investigators  who  made  the  discovery.  They  re- 
semble enzymes  and  have  the  power  to  decompose  certain  sub- 
stances characteristically  just  the  same  as  the  ferment  deposited 
by  the  yeasts.  These  active  albimiens  are  destroyed  by  212°  F. 
and  become  passive. 

This  discovery  is  valuable  to  the  manufacturer  of  food  pro- 
ducts, since  it  throws  a  flood  of  light  on  many  cases  of  poisoning 
blamed  on  canned  goods.  Many  people  eat  uncooked  meat  in  the 
so-called  ''cannibal  sandwiches,"  smoked  sturgeon  and  halibut,  and 
m  the  same  meal  eat  canned  goods.  If  poisoning  results,  too  often 
the  blame  is  fastened  on  them,  which  causes  considerable  criticism 
of  canned  goods.  Pathogenic  organisms  find  their  way  into  milk 
and  on  some  raw  vegetables,  due  to  sprinkling  with  contaminated 
water,  and  the  active  albumen  formed  often  causes  severe  cramps 
and  even  death.  Cholera  infantum  is  probably  the  result  of  con- 
taminated milk;  indeed,  the  common  potato  bacillus,  Mesentericus 
Vulgatus,  is  capable  of  causing  severe  intestinal  complications  where 
milk  containing  it  is  given  to  infants  in  nursing. 

There  have  been  cases  of  ptomaine  poisoning,  however,  which 
could  possibly  be  traced  to  canned  goods.  There  have  been  and 
possibly  are  today  packers  of  canned  goods  who  either  are  ignorant 
of  the  danger  of  canning  unsound  products  or  else  they  are  un- 
scrupulous. Such  men  cause  a  great  deal  of  trouble  to  the  industry 
as  a  whole,  for  all  must  sufl:*er  the  severe  criticisms  of  the  press  and 
must  battle  against  unjust  legislation.  A  National  Canner's  As- 
sociation could  put  a  stop  to  such  practices. 

I  know  personally  one  packer  of  meats  and  sausages  who  was 
arrested  a  number  of  times  for  attempting  to  use  contaminated 
material.  "No  one  would  known  the  difference  after  it  is  canned," 
was  his  expression.  There  is  no  telling  how  much  trouble  this 
man  may  have  caused,  and  it  would  hardily  be  supposed  that  there 
were  no  cases  of  poisoning  where  his  goods  were  marketed.  H^ 
used  fictitious  labels  and  covered  his  name  so  that  it  would  be 
difiicult  to  trace  any  complaints. 

!  Such  men  should  be  forced  to  either  put  up  wholesome  goods 

I  under  their  own  names  or  be  compelled  to  get  out  of  the  business, 
and  to  accomplish  this  the  law  demanding  the  name  of  the  manu- 
facturer to  be  printed  on  his  labels  is  wise  and  beneficial.   There 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  163 

zvoiild  be  no  advantage  in  dating  such  goods,  for  unsound  goods 
could  not  he  detected  by  a  date  on  the  can. 

There  should  be  great  care"  exercised  in  the  selection  of  all 
raw  materiaT,  especially  such  as" contains  albumen  and  is  liable  to 
piitrefacdon.  There  are  means  of  knowing  when  raw  materiaf  is^ 
good,  both  from  general  appearance  and  microscopical  examination. 
Every  canner  should  possess  a  good  microscope,  with  an  improved 
oil  immersion  lens. 

There  are  a  number  of  bacteria  associated  with  meat  poisoning 
which  we  will  now  describe,  and  these  may  be  studied  carefully, 
as  the  plates  and  descriptions  will  serve  as  a  guide  and  reference. 

One  of  the  most  common  germs  which  produces  a  ptomaine  is 
P?'o teusn^id^qris,  found  in  putrefying  meat.  The  rods  are  gener- 
ally found  in  pairs.  They  measure  0.9 — i.2,u.  in  length,  0.4 — 0.6/* 
in  breadth,  but  occasionally  forms  are  seen  6iU-  long  and  they  fre- 
quently form  threads  (100  /a  long)  when  cultivated  in  nutrient  ge- 
latin. Spirilla,  or  curved  threads,  spirulina,  or  twisted  threads, 
are  also  seen  in  gelatin  cultures.  Involution  forms  with  swelled 
ends  resembling  dumb-bells  and  lemons  are  met  with.  The  colonies 
on  gelatin  show  the  twisted  and  straight  threads  growing  out  from 
the  center  and  these  sometimes  move  out  into  the  gelatin,  becom- 
ing detached,  so  that  the  name  of  '' Swarming  Islands"  had  been 
given  to  them.  The  detached  colonies  sometimes  resemble  curious 
designs  and  figures  and  the  name  of  "Bacillus  figurans"  has  been 
given  the  germ  on  account  of  this  peculiarity. 

It  is  aiY^ctively  motile  organism  on  account  of  the  large  num- 
ber of  flagella  it  possesses  which  radiate  from  the  whole  surface 
of  the  celL 

The  motion  is  seen  to  be  in  two  directions;  it  turns  on  its 
long  axis  and  moves  rapidly  forward  at  the  same  time.  There  is 
no  spore  formation  and  the  cell  life  is  easily  destroyed  by  a  moist 
t'emperature  of  150°  F. ;  in  fact  135°  F.  kills  it  in  a  few  minutes. 
It  is  a  facultative  anaerobe  and  grows  well  at  70°  to  98°  F.,  best 
at75_^_tp_8ol.E.  It  is  stained  well  with  carbol  fuchsin,  but  Gram^s 
method  is  negative. 

On  Gelatin  Plates  it  forms  small  round,  yellowish  colonies 
with  thick  centers,  with  the  peculiarities  before  mentioned.  The 
Gelatin  is  rapidly  Hquefied,  both  in  plate  and  stab  cultures. 

On  Agar  a  moist  gray  layer  is  formed,  spreading  rapidly  over 
the  entire  surface. 

On  Potato  a  grayish  coating  forms. 

Bouillon  is  uniformly  clouded.     Milk  is  coagulated  and  made  ' 
faintly  acid.    It  produces  large  quantities  of  sulphuretted  hydrogen 
and  forms  indol ;  grows  well  in  the  presence   of   hydrogen   and  | 
carbonic  acid,  and  the  odor  from  all  media  is  abominable. 


166  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


Proteus  Vulgaris,  Hauser 

Origin. — It  is  very  widely  distributed ;  is  commonly  present  in  the 
putrefaction  of  animal  proteins ;  has  also  been  found  in  water,  in  ijiec.on- 
ium,  in  purulent  abscesses,  and  in  the  blood  and  tissues  of  several  cases 
of  fatal  putrid  infection  of  the  intestines. 

Form. — Rods  varying  in  length  from  short  oval  forms  to  those  which 
are  two  to  six  times  as  long  as  wide.  Grows  in  pairs,  is  usually  bent; 
sometimes  forms  twisted,  interwoven  threads.  Roundish  involution  forms 
are  commonly  found. 

Motility. — Actively  motile,  with  from  sixty  to  one  hundred  flagella, 
arranged  all  over  the  surface. 

Sponilation. — Not  observed.  Cultures  are  resistant  to  dessication  and 
retain  vitality  for  many  months. 

Anilin  Dyes. — Stain  readily.     Will  not  stain  by  Gram's*method. 

Grozuth. — Very  rapid. 

Gelatin  Plates. — Gelatin  is  rapidly  and  extensively  liquefied.  The 
colonies  are  of  a  yellowish-brown  color,  having  bristly  borders ;  in  soft 
gelatin  they  have  a  tendency  to  spread  over  the  surface,  forming  peculiar 
figures.  Detached  portions  of  the  colonies  may  be  observed  to  move 
about,  which  has  gained  for  them  the  name  of  "swarming  islands."'  A 
disagreeable  odor  is  noticeable.     They  have  an  alkaline   reaction. 

Stab  Culttire. — Liquefaction  extends  along  the  entire  line  of  inocula- 
tion; it  is  very  rapid,  and  the  whole  contents  are  liquefied  in  a  few  days. 
The  liquid,  which  is  at  first  diffusely  cloudy,  clears  up  later  and  a  flocculent 
sediment  settles  on  the  bottom.  At  the  same  time  a  grayish-white  layer 
is  formed  on  the  top. 

Streak  Culture. — On  agar,  a  grayish,  slimy,  rapidly  spreading  growth 
is  formed.     On  potato,  it  forms  a  dirty  colored,  sticky  covering. 

Oxygen  Requirements — It  is  a   faculative  anaerobe. 

Temperature. — The  optimum  is  between  20°  and  24°  C. ;  it  grows  very 
well  in  the  incubator. 

Behavior  to  Gelatin. — Liquefies  rapidly. 

Aerogenesis. — Hydrogen  sulphide  is  formed. 

Pathogenesis. — It  has  no  effect  in  small  doses.  Toxic  effects  and 
even  death,  are  produced  by  the  injection  of  large  quantities  of  living  or 
filtered  in  rabbits  and  guinea-pigs.  It  is  toxicogenic  and  sometimes  may 
be  pathogenic. 

This  and  several  related  are  included  in  the  Bacterium  termo  of  the 
older  writers. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  16^ 


Plate  51.     Proteus  Vulgaris,   Flagellated 

Photomicrograph  showing  proteus  vulgaris  which  produces  a  ptomaine.     Magnified  1,500  diameters. 


Plate  52.     Proteus  Vulgaris,  showing  "  Swarming  Islands. 

Contact  staining  by  the  author.     Magnified  75  diameters. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  169 

Pathogenesis.  Animals,  when  subject  to  intravenous  injec- 
tions of  Proteus  cultures,  die  of  acute  enteritis  and  peritonitis,  pre- 
viously exhibiting  typical  symptoms  of  poisoning,  such  as  bloody 
vomiting  and  diarrhoea,  combined  with  severe  tremors  and  feverish 
temperature. 

The  toxin  is  no  doubt  of  a  poisonous  nature  and  is  not  de- 
stroyed by  heat,  even  after  the  bacilli  have  perished.  Patients 
suffering  from  '^Weil's  disease"  are  afflicted  with  this  parasite, 
which  may  be  obtained  from  the  pus  and  urine. 

PROTEUS   MIRABILIS. 

Proteus  Mirabilis  greatly  resembles  the  organism  just  describ- 
ed, yet  has  distinct  characteristics.  The  rods  are  various  lengths, 
closely  resembling  vulgaris,  but  the  threads  are  much  longer,  often 
attaining  a  length  of  200^1.  They  are^  motile  and  possess  many 
flagella.  Spore  formation  is  absent.  The  Gelatin  plates  and  stab 
cultures  are  slowly  liquefied.  The  deep  colonies  from  curiously 
twisted  masses  or  zooglea. 

Large  quantities  of  sulphuretted  hydrogen  are  formed.  Cul- 
tures show  a  decided  indol  reaction;  milk  is  coagulated  with  faint 
acidLieaction.  Bacilli  grow  fairly  well  in  an  anaerobic  state,  either 
in  hydrogen  or  carbonic  acid  gas.  They  are  found  in  putrefactive 
processes  and  produce  a  toxin  similar  in  its  pathogenic  effects  to 
that  elaborated  by  Proteus  Vulgaris.  The  odor  produced  when 
cultivated  on  all  nutrient  media  is  very  foul. 

PROTEUS    ZENKERI. 

Proteus  Zenkeri,  called  by  some  authors  Bacterium  Zopfii,  is 
a  bacillus  o.4iit  broad  and  about  1.5/^  long,  resembling  the  two  pre- 
ceding species,  but  it  is_smaller  and  does  not  liquefy  gelatin.  It 
occasionally  forms  ''Swarming  Islands"  like  the  other  two  and  the 
other  biological  characteristics  are  similar.  It  is  a  peritrichous 
(many  flagella)  organism  and  produces  a  specific  poison. 

These  three  germs  belonging  to  the  Proteus  family  are  re- 
markable for  their  rapid  boring  movements.  They  swarm  through 
media  which  are  solid  enough  to  confine  most  motile  bacteria.  Our 
readers  will  be  able  from  these  descriptions  and  plates  to  recognize 
any  of  them  under  the  microscope  either  in  plates  or  in  stained 
preparations.  Other  bacteria  associated  with  Ptomaine  and  Toxic 
poisons. 

BACILUUS  BOTULINUS. 

This  putrefactive  organism  was  discovered  by  Van  Ermengem 
during  an  epidemic  of  poisoning  from  meats  at  Ellezelles  in  Bel- 


170  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


Bacillus  Mirabilis 

Origin. — It  is  very  ^videly  distributed ;  is  commonly  present  in  the 
putrefaction  of  animal  proteins ;  has  also  been  found  in  water,  in  mecon- 
ium, in  purulent  abscesses,  and  in  the  blood  and  tissues  of  several  cases 
of  fatal  putrid  infection  of  the  intestines. 

Form. — Rods  varying  in  length  from  short  oval  forms  to  those  which 
are  two  to  six  times  as  long  as  wide.  Grows  in  pairs,  is  usually  bent; 
sometimes  forms  twisted,  interwoven  threads,  longer  than  Vulgaris. 
Roundish  involution  forms  are  commonly  found. 

Motility. — Actively  motile,  with  from  sixty  to  one  hundred  flagella, 
arranged  all  over  the  surface. 

Sponilation. — Not  observed.  Cultures  are  resistant  to  dessication  and 
retain  vitality  for  many  months. 

Anilin  Dyes. — Stain   readily.     Will   not   stain  by   Gram's   method. 

Growth. — Very  rapid. 

Gelatin  Plates. — Gelatin  is  slowly  liquefied.  The  colonies  are  of  a 
3-cllowish-brown  color,  having  bristly  borders ;  in  soft  gelatine  they  have 
a  tendency  to  spread  over  the  surface,  forming  peculiar  figures.  De- 
tached portions  of  the  colonies  may  be  observed  to  move  about,  which 
has  gained  for  them  the  name  of  "swarming  islands."  A  disagreeable 
odor  is  noticeable.     They  have  an  alkaline  reaction. 

Stab  Culture. — Liquefaction  extends  slowly  along  the  entire  line  of 
inoculation. 

Streak  Culture. — On  agar,  a  grayish,  slimy,  rapidly  spreading  growth 
is  formed.     On  potato,  it  forms  a  dirty  colored,  sticky  covering. 

Oxygen  Requirements.— \t  is  a  facultative  anaerobe. 

Temperature. — The  optimum  is  between  20°  and  24°  C. ;  it  grows  very 
well  in  the  incubator. 

Behavior  to  Gelatin. — Liquefies  rapidl^^ 

Aerogenesis. — Hydrogen  sulphid  is  formed. 

Pathogenesis. — It  has  no  effect  in  small  doses.  Toxic  effects  and  even 
death  are  produced  by  the  injection  of  large  quantities  of  living  or  filtered 
in  rabbits  and  guinea-pigs.  It  is  toxicogenic,  and  sometimes  may  be 
pathogenic. 

This  and  several  related  are  included  in  the  Bacterium  termo  of  the 
older  writers. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS. 


171 


Plate  53.    Proteus  Mirabilis,  Flagellated 


Photomicrograph  of  proteus  mirabilis,  an  organism  which  produces  a  ptomaine.     Isolated  from  putrefying 
meat.     Magnified  1,200  diameters. 


Plate  54.     Proteus  Mirabilis,  showing  "  Swarming  Islands. 
Contact  staining  by  the  author.     Magnified  75  diameters. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  173 

gium.  The  peculiar  symptoms  exhibited  by  the  unfortunate  vie-/ 
tims  of  the  botuhnus  group  of  bacteria,  are  nervousness  of  central  \ 
origin,  disturbances  in  the  muscular  system,  the  salivary  and  other  j 
secretions  are  suspended;  difficulty  in  swallowing;  hoarseness,  my- 1 
driasis  and  ptosis,  and  death  sometimes  follows.  The  origin  of  \ 
^'botuhsiillLlias^heen  traced  to  contaminated  salt  fish,  smoked  meat, 
such  as  ham,  preserved  meats,  blood  and  liver  sausages,  etc. 

Bacilli  botulini  are  seen  under  the  microscope  as  large  motile 
rods  measuring  4  to  6fj-  long  and  0.9  to  i.2fji  in  thickness,  having 
rounded  ends.  Various  involution  (odd  shaped)  forms  are  some- 
times seen.  Threads  are  rarely  formed,  though  sometimes  three 
to  ten  rods  will  remain  united. 

When  properly  stained  four  to  eight  flagella  can  be  counted, 
which  give  the  bacillus  a  creeping  motion.  It  stains  readil}^  with 
nearly  alljcplors,  and  also  by  Gram's  method  (see  article  on  stain- 
ing) where  alcohol  is  not  used  to  excess. 

It  forms  spores  which  are  ellipsoidal  and  are  situated  in  the 
ends  of  the  rods  (terminal  spores).     They  are  rarely  median. 

The^yegetating  forms  are  killed  in  boiling  temperature  212° 
F.,  but  the  spores  are  more  resistant.  250°  F.  kills  them  in  a 
very  few  minutes. 

Bacillus  botulinus  is  anaerobic  and  grows  well  at  75°  to  85° 
F^^but  will  grow  without  sporulation  at  98°  F.  Involution  forms 
appear  at  blood  temperature.  The  best  artificial  media  for  culti- 
vation are  made  slightly  alkaline  with  an  addition  of  2  per  cent, 
grape  sugar.  It  produces  butyric  acid  and  a  toxic  poison  which 
can  be  precipitated  in  almost  pure  state  by  treating  a  bouillon  cul- 
ture with  absolute  alcohol,  neutral  salts  and  tannic  acid. 

Gelatin  plate  culture;  round,  transparent,  brownish  yellow 
colonies  make  their  appearance  in  four  or  five  days.  These  colonies 
have  a  thick,  lustrous,  granulated  appearance,  slightly  liquefying 
the  surrounding  gelatin.  When  magnified  sixty  times  the  margins 
appear  slightly  irregular  and  radiating.  In  the  stab  cultures  the 
course  of  the  needle  shows  a  white  growth  extending  into  the  sur- 
rounding gelatin,  which  is  liquefied  with  the  evolution  of  consider- 
able gas. 

Grape  Sugar  Bouillon  is  clouded  very  much ;  in  milk  there  is 
no  coagulation  and  it  remains  unaltered. 

Pathogenesis — Guinea  pigs,  cats,  mice  and  dogs  are  killed  by 
inoculation  with  the  poison  and  also  with  the  pure  cultures.  The 
nerve  centers  are  greatly  affected,  principally  the  medulla  oblongata, 
the  ganglion  of  the  hypolossal  nerve,  the  dorsal  ganglion  of  the 
vagus,  the  small-celled  ganglion  of  the  motores  oculorum  and 
brain  nerves. 


174  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


Bacillus  Zenker! 

OrigiJi. — Found  in  intestines  of  chickens ;  also  in  feces,  water  and 
putrefying  substances. 

Form. — Rods,  two  to  five  times  as  long  as  wide.  Threads  are  formed; 
in  gelatin  they  are  often  bent  or  twisted  in  peculiar  shapes,  resembling 
spirals.     Coccus-like  involution  forms  abound  in  old  cultures. 

Motility. — Actively  motile. 

Spornlotion.— Involution  forms  are  found  which  resemble  spores. 
These  are  said  to  resist  dessication,  but  are  easily  destroyed  by  heat,  and 
stain  readily  with  anilin  dyes. 

Anilin  Dyes. — Stain  readily. 

Groivtii. — Rapid. 

Gelatin  Plates. — Delicate,  cloudy  patches  of  radiating  threads  are 
formed  by  the  colonies,  which  show,  under  the  microscope,  in  addition  to 
these,  numerous  small,  rounded  bunches  of  cells. 

Stab  Culture. — There  is  a  marked  growth  in  the  upper  part  of  the 
tube,  but  none  in  the  lower  part;  fine  radiating  lines  penetrate  into  the 
gelatin,  most  deeply  at  or  near  the  surface. 

Streak  Culture.     On  agar,  a  very  thin,  dry,  grayish  growth  is  formed. 

Oxygen  Requirements. — It  is  an  obligative  anaerobe. 

Temperature. — Grows  best  at  ordinary  temperature.  Will  grow  at  37° 
to  40°  C.  but  has  a  tendency  to  develop  involution  forms  and  to  die  out. 

Behavior  to   Gelatin. — Does  not  liquefy.     No  indol. 

Pathogenesis.     Produces  a  ptomaine. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  175 

Bacillus  botulinus  is  sometimes  found  in  putrefying"  meat,  gen- 
eraljy  in  the  lean  parts,  seldom  ifi  the  fat,  and  is  able  to  flourish 
when  the  surface  is  covered  with  the  aerobic  putrefactive  bacteria, 
which  use  up  the  oxygen  and  make  the  conditions  favorable  within 
the  tissue  for  the  development  of  anaerobic  species. 

This^ bacillus  is  particularly  dangerous  from  the  fact  that  Jt 
foin^s_sjDores  which  will. Jive_  through  pickling  and  smoking  pro- 
cesses and  will  afterward  develop.  Van  Ermengem  discovered  the 
bacillus  m  a  ham  w'hich  had  poisoned  a  number  of  people. 

Albuminous  foods,  if  properly  handled  in  the  raw  state,  will 
not  stiffer_from  this  orgaiiism.  Exposure  to  putrefaction  is  dan- 


f  t  ^ 


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f 


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,       •* 


# 


mt 


Plate  55.     Proteus  Zenkeri,  Flagellated 

Photomicrograph  of  Proteus  Zenkeri,  an  organism  which  produces  a  ptomaine.       Isolated  from  putrefying 
meat  in  a  leaky  can.     Magnified  1,200  diameters. 


BACII.I.US  ENTHRITIDIS. 

Bacillus  enteritidis  belongs  to  the  Coli  group.  It  was  discov- 
ered in  1888  by  Gartner  in  a  meat  poisoning  epidemic.  He  ob- 
tained it  from  the  tissue  of  a  cow,  which  died  of  mucous  diarrhoea, 
and  from  the  spleen  of  a  man  w^ho  had  died  from  eating  its 
flesh.  It  is  morphologically  identical  wath  the  Bacterium  Cqli  JDys- 
entericum,  which  has  been  proved  To  Bejhe  cause  of  epidemics  of 
dyseiitery.  -^ --  — 

Bacillus  enteritidis  has  been  found  to  be  the  cause  of  many 
cases  of  poisoning  from  meats;  it  appears  as  rods  2  to  4/^  long  and 
0.4  to  0.6/x  broad.  The  ends  are  rounded  and  are  refractive, 
especially  when  the  organism  is  cultivated  on  gelatin  and  examined 
in  the  hanging  drop  culture.     It  possesses  five  to  ten  flagella  and 


176  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


Plate  56.     Bacillus  Botulinus,  showing  Flagella 

An  organism  which  produces  a  poisonous  ptomaine. 


Plate  57.     Bacillus  Botulinus,  showing  Rods  and  Spores 

Magnified  1,200  diameters. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  177 

is  motile.  (This  is  denied  by  Lehman  and  Neumann.)  Their  error 
is  possibly  due  to  investigating  old  cultures.  Cultures  twenty-four 
hours  old  show  a  true  independent  motion  and  flagella  can  be  de- 
monstrated by  the  method  of  staining  (described  in  Chapter  III). 
The  rods  stain  more  deeply  in  the  middle  than  in  the  ends,  due  to 
their  richness  in  fat  of  alkaline  nature.  An  even  stain  may  be 
made  by  first  treating  the  germs  with  a  20  per  cent,  solution  of 
Sulphuric,  Acid,  H2SO4,  which  neutralizes  the  alkaline,  and  the 
stain  takes  quite  readily  afterwards.    Gram's  method  is  negative. 

It  grows  well  in  temperatures  ranging  from  70°  to  100°  F., 
hest.at  98°  F.  Gelatin  Plates  show  the  superficial  colonies  as  thin, 
almost  transparent  films,  and  there  is  no  liquefaction  of  the  gelatin, 
either  in  plates  or  Stab  Culture.  There  is  very  little  odor  in  any 
of  the  culture  media. 


^ 


«4#.     *?^^' 


V 


>' 


Plate  58.     Bacillus  Enteritidis 
Photomicrograph  of  an  organism  which  produces  a  deadly  poison.     Magnified  1,000  diameters. 

AGAR  PLATE  cultures  show  a  gray  film,  almost  transparent. 
Bouillon  cultures  is  uniformly  clouded.  Grape  sugar  bouillon  is 
acidified  with  the  evolution  of  Carbonic  Acid  Gas  and  a  combusti- 
ble gas  similar  to  marsh  gas.  Milk  vSugar  Bouillon  is  not  acidified, 
but  the  same  gases  are  formed  less  abundantly. 

MILK  is  not  coagulated  nor  changed  chemically.  Young  cul- 
tures do  not  form  indol;  old  cultures  show  slight  traces.  It  is  an 
aerobic  organism,  facultative  anaerobic  in  the  presence  of  grape 
sugar. 


178  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

PATHOGBNBSIS. — When  this  organism  grows  on  meat  a 
powerful  ptomaine  poison  is  found  which  heat  does  not  destroy. 
Even  the  broth  from  such  meat  will  contain  the  poison.  The  poison 
may  be  precipitated  with  absolute  alcohol,  tannic  acid  and  neutral 
salts,  if  acid  is  present. 

Live  cultures  of  the  germs  when  inoculated  subcutaneously  in- 
to small  animals  cause  death  in  three  to  eight  days.  Intravenous 
injections  of  the  ptomaine  result  the  same.  Infected  meat  fed 
to  animals  causes  intense  gastro-enteric  cramps  and  death.  These 
%mptoms  are  the  same  in  man.  This  form  of  meat  poisoning 
follows  the  consumption  of  meat  obtained  front  diseased  animals. 

Owing  to  the  imperceptible  decomposition  set  up  by  bacillus 
enteriditis  it  is  indeed  a  dangerous  organism.  It  may  be  present  in 
ham  sausage  and  fresh  meat  without  any  outward  indication  of  its 
presence.  The  milk  obtained  from  diseased  animals  may  contain 
the  germs  and  to  all  appearances  it  may  seem  good.  Canners  of 
meat  are  menaced  by  such  an  organism  and  need  inspectors  to 
examine  all  meat  that  is  used.  The  same  applies  to  the  canners  of 
assorted  soups,  where  meat  is  used  for  the  stock.  Manufacturers 
of  these  goods  ought  to  have  a  man  to  inspect  and  examine  micro- 
scopically, all  jTieats_.used. 

Not  all  cases  of  gastro-enteric  disturbances  prove  fatal  or 
even  serious.  Nearly  every  person,  at  times,  is  subject  to  these, 
and  it  is  safe  to  say  that  ptomaines  are  responsible  in  fully  one- 
third  of  the  cases,  but  the  causes  are  not  understood  and  are  passed 
by.  It  is  only  when  severe  cases  are  brought  to  the  attention  of 
the  public  that  any  criticisms  are  published.  Ptomaines  are  most 
frequently  formed  in  raw  material  bought  in  the  open  market. 
Eternal  vigiliance  is  the  only  safeguard  for  the  manufacturers  w^ho 
use  albuminous  material.  It  is  well  to  state  here  that  such  dis- 
turbances as  we  have  described  may  result  from  other  causes; 
overheating  incompatible  foods,  and  drinking  too  much  liquor  often 
cause  complications  of  this  nature. 

BACIIyI,US    MORBI^ICANS    BOVIS. 

This  organism  was  isolated  by  Basenan  from  the  tissue  and 
spleen  of  a  cow  which  died  of  puerperal  fever.  It  is  biologically 
and  morphologically  the  same  as  the  Bacterum  of  swine  cholera. 
Ostertag  found  that  ptomaine  poisoning  was  produced  where  the 
flesh  of  cows  affected  with  puerperal  fever  had  been  eaten. 

It  is  an  actively  motile  organism,  having  8  to  14  flagella,  the 
rods  measuring  0.3  to  0.4^1  broad  and  i  to  1.2/x  long,  generally 
united  in  pairs.  (It  resembles  the  typhoid  bacillus).  Spore  for- 
mation has  not  been  observed.  It  stains  readily  with  all  ordinary 
dyes,  but  Gram's  method  is  negative. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  179 

Colonies  on  gelatin  and  agar  resemble  those  of  Bacterium  coli, 
but  have  a  more  granular  appearance.  Gelatin  is  not  liquefied. 
Agar  stab  cultures  have  white  tufts.  Bouillon  is  clouded  and  a 
thin  pellicle  is  formed  on  the  top.  Cultures  on  sterile  potato  are 
yellow  and  moist  and  do  not  darken.  Milk  is  not  coagulated. 
Grape  sugar  is  slightly  fermented  with  two  gases  liberated.  Carbonic 
acid  and  Hydrogen.  Cane  sugar  is  not  fermented.  Indol  and 
Phenol  are  not  formed.  The  bacillus  is  killed  at  boiling  tempera- 
ture^and^even  at  i6o°  F.,  but  the  ptomaine  is  not  so  destroyed. 
Both^the^eat  and  the  milk  from  diseased  cows  will  retain  the 
goisSi^^  Very  small  animals  are  killed  by  inoculation  or  from  eat- 
ing the  flesh ;  dogs  and  cats  are  not  affected.  The  same  precautions 
we  have  mentioned  previously  will  prevent  poisoning  from  this 
saprophyte. 

m  ^ 


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f 


Plate  59.     Bacillus  Morbificans  Bovis,  Flagellated 

Magnified  1,000  diameters. 

BACILLUS   MALI.KI. 

This  is  the  bacillus  which  causes  glanders  and  produces  a  toxic 
poison  which  is  fatal  to  some  animals  whose  flesh  is  used  as  food, 
viz.,  sheep  and  pigs.  The  horse  is  very  susceptible  and  man  also, 
but  our  object  is  to  show  its  association  with  meat  poisoning.  The 
bacillus  was  dicovered  by  Loeffler  and  Schutz  and  occurs  as  non- 
motile  rods  2  to  3/A  long  and  0.4W  broad,  showing  bright  shining 


180  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

Bacillus  Mallei,  Loeffler  and  Schutz,  (1882) 
glanders;  morve  (fr.)  ;  ROtz  (germ.),  malleus  (lat.). 

Origin. — It  is  found  in  the  nodules,  ulcers,  discharges,  etc.,  of  glanders. 

Form. — Straight  or  slightly  curved  rods,  with  rounded  ends,  shorter 
and  thicker  than  the  tubercle  bacillus.  Usually  single,  but  may  grow  in 
pairs  or  in  short  threads. 

Motility. — Marked  Brownian  motion. 

Sporiilation. — Bright  bodies,  considered  by  Loeffler  as  the  first  indi- 
cation of  degeneration,  are  often  found  in  the  cells,  but  real  spores  have 
not  been  found.     It  is  not  very  resistant  to  dessication. 

Anilin  Dyes. — It  stains  unevenly  and  is  rapidly  decolored.  Carbolic 
fuchsin,  alkaline  aniline  gentian  violet,  or  anilin  fuchsin,  stain  well,  es- 
pecially when  warmed.     Does  not  stain  by  Gram's  method. 

Growth. — Grows  best  at  relatively  high  temperature.  Rapid.  Grows 
best  on  glycerin  agar. 

P/a/^.y.— Excellent  colonies  form  in  a  day  or  two  on  glycerin  agar  at 
37"^.  The  colonies  are  round,  grayish  and  glistening,  having  smooth  sharp 
borders  and  with  granular  contents.  Colonies  cannot  be  obtained  on  gel- 
atin, as  a  rule. 

Stab  Culture. — Develops  very  slowly  in  gelatin ;  can  be  made  in  gly- 
cerin agar. 

Streak  Culture. — On  glycerin  agar  a  thick,  moist,  slimy  growth  is 
formed.  On  potato  it  forms  a  thin,  transparent,  amber-colored  growth, 
which  later  becomes  a  reddish-brown.  On  blood-serum  yellowish,  trans- 
parent spots  are  formed ;  these  later  run  together,  yielding  a  slimy,  whitish 
growth. 

Bouillon. — Grows  readily  and  abundantly,  with  diffuse  cloudiness ;  ring 
of  slime  on  the  surface.  Mallein  is  the  filtered  bouillon  of  the  glanders 
bacillus.     It  is  analogous  to  tuberculin. 

In  milk  and  acid  reaction  is  produced. 

Oxygen  Requirements. — It  is  a  facultative  anaerobe. 

Temperature. — Grows  best  at  about  2>7°  C.  Does  not  grow  readily 
above  42°  or  below  25°  C. 

Behavior  to  Gelatin. — There  is  very  slight  growth  at  first,  but  may  be- 
come accustomed  to  growth  at  room  temperature  later. 

Attenuation. — Takes  place  rapidly  when  grown  on  artificial  media. 
If  the  bacillus  is  not  frequently  passed  through  an  animal  the  virulence 
is  lost  and  the  organism  may  die  out. 

Immunity. — Intravenous  injections  of  small  amounts  of  bouillon  cul- 
ture render  dogs  immune. 

Pathogenesis. — Man,  horse,  ass,  goats,  cats,  guinea-pigs  and  field- 
mice  are  highly  susceptible.  Cattle,  hogs,  ordinary  and  white  mice  are 
immune.  Dogs,  rabbits  and  sheep  are  slightly  susceptible.  White  mice 
fed  with  phloridzin  become  susceptible.  On  inoculation  susceptible  ani- 
mals develop  typical  glanders.  In  guinea-pigs  death  will  result  in  four 
to  eight  weeks.  Field  mice  die  within  a  few  days.  Enlarged  lymphatics, 
nodules  in  liver,  spleen,  etc.     Bacilli  are  present. 

Infection. — May  occur  through  wounds — inoculation  glanders.  A  man 
was  accidentally  and  fatally  inoculated  with  a  pure  culture  in  one  instance. 
The  usual  source  of  infection  in  horses  is  probably  along  the  respiratory 
tract. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  181 

granules,  which  are  not  spores,  although  some  authors  have  erred 
in  so  stating.  The  rods  generally  appear  singly  with  rounded  ends. 
Pairs  are  sometimes  seen  and  rarely  threads.  Sometimes  branch- 
ing threads  are  seen  in  old  cultures.  The  bacillus  stains  somewhat 
difficultly  with  ordinary  dyes  and  Gram's  method  is  negative.  It 
greatly  resembles  the  Diphtheria  bacillus  in  staining  on  account 
of  the  granules  before  mentioned. 

It  is  aerobic,  facultative,  anaerobic:  grows  at  any  tempera- 
ture between  yj^  F.  and  io8°  F.,  best  at  blood  heat,  on  5  per  cent, 
glyceriiie  a^r. 


Plate  60 


Photomicrograph  of  Bacillus  mallei,  showing  bright,  shining  granules,  resembling  spores.     Stained  with 
Loeffier's  menthyline  blue.     Magnified  1,000  diameters. 

A  characteristic  growth  is  exhibited  on  sterile  potato  at  98° 
F.,  when  moist  amber-colored  patches  make  their  appearance;  these 
deepen  to  a  red  brown  and  become  thicker,  sometimes  forming  in- 
terlaced threads.  The  surface  surrounding  the  growths  turns  quite 
dark.  Acid  is  produced  in  media  containing  grape  or  milk  sugar. 
Bouillon  is  made  slightly  cloudy  with  a  sediment  (and  a  trace  of 
indol).  Milk  is  coagulated  slowly  and  separated  into  casein  and 
clear  whey,  owing  to  the  production  of  acid.  No  gas  is  formed 
from  carbohydrates. 

The  Bacillus  Mallei  is  destroyed  at  2i2°F.  in  a  few  minutes, 
but  the  specific  poison  is  still  virulent.  This  toxin  has  been  separated 
by  filtration  and  is  called  Mollein  and  is  analogous  by  the  tuber- 


182  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

culin  of  the  tubercle  bacillus  obtained  by  Dr.  Koch  of  Berlin.  Mal- 
lein  is  used  in  cases  of  glanders  as  a  cure  and  gives  good  results 
in  early  stages  of  the  disease.  It  is  also  used  as  a  means  of 
diagnosis  of  glanders  in  animals. 

Sheep  and  pigs  are  susceptible  and  should  these  be  slaughtered 
and  the  meat  be  consumed,  severe  cases  of  poisoning  would  result. 
The  poison  would  remain  virulent  in  the  meat  even  after  cooking 
or  canning.  Pork  is  used  largely  in  the  preparation  of  canned 
pork  and  beans.  Great  care  and  judgment  should  be  exercised  in 
the  selection  of  the  pork.  Good  pork  has  a  firm  and  healthy 
appearance  in  the  pickle  and  the  presence  of  bruises,  soft  spots  or 
3isease  growths  should  immediately  condemn  it  as  not  fit  to  use. 
Do  not  cut  out  the  bad  parts  and  use. the  piece,  but  refuse  the  whole 
tierce  if  there  are  any  such  characteristics.  Some  packers  are  tem- 
pted to  use  inferior  pork,  because  the  price  is  a  few  cents  less  per 
pound.  Use  only  select  pork  and  the  general  appearance  will  be  a 
good  indication  of  its  wholesomeness.  Of  course,  the  microscope 
should  be  used  constantly  to  determine  the  character  of  the  albumin- 
ous material  used  in  canning,  and  this  applies  to  the  examination 
of  pork  particularly,  in  the  detection  of  bacteria  as  well  as  the 
deadly  trichinae. 

Our  readers  have  now  become  acquainted  with  some  of  the 
germs  which  produce  ptomaines  and  toxins,  but  there  remain  a 
few  belonging  to  the  Pa.thogenic  class,  which  are  at  times  epidemic 
and  are  familiar  to  everyone  as  the  cause  of  special  diseases.  Their 
description  and  biological  characters  will  be  interesting,  not  only  in 
connection  with  out  subject  at  hand,  but  also  from  a  bacteriological 
standpoint. 

OTHER    PATHOGENIC    BACTERIA    ASSOCIATED    WITH    PUTREFACTION 
AND  EOOD  POISONING. 

There  are  a  number  of  bacteria  which  are  pathogenic  biit  are 
able  to  grow  on  certain  food  and  in  water,  where  they  form  poisons 
which  are  nearly  related  to  ptomaines.  Some  of  them  form  toxins 
which  act  as  poisons  and  these  may  be  formed  in  food  which  seems 
to  be  wholesome  in  every  respect.  It  often  happens  that  the  bac- 
teria are  carried  in  the  food  and  cause  epidemics  of  disease,  and 
the  description  of  several  common  varieties  will  be  interesting  to 
the  student  of  foodstuff  for  this  reason. 

TYPHOID  BACILLUS. 

This  organism  was  discovered  by  Eberth  in  the  internal  organs 
of  persons  who  had  died  of  typhoid  fever.  The  bacillus  was  ob- 
served by  Dr.  Koch  in  the  typhoid  abscesses  and  he  made  photomi- 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  183 

crographs  of  it.  The  typhoid  bacillus  is  particularly  interesting  to 
the  student  of  bacteriology  and  may  be  obtained  in  pure  cultures 
in  the  manner  we  shall  describe  later  (article  on  plate  culture). 

It  occurs  as  short  plump  rods  with  rounded  ends,  singly,  some- 
times in  pairs,  and  when  grown  on  potato  in  threads.  It  measures 
from  I  to  3/^  long  and  0.5  to  0.9/^  broad.  It  grows  on  agar  well 
at  q8°  F.  and  this_  cuUure  gives  the  most  satisfactory  results  for 
flagella  staining.  Bright  shining  spots  are  seen  at  the  ends  of  the 
bacillus  and  these  were  thought  to  be  spores  by  Gaffky,  but  such 
isjigtthe_^case. 

It  is  actively  motile,  possessing  eight  to  eighteen  flagella,  which 
give  the  short  rods  a  wonderfully  rapid  motion.  It  travels  very 
fast,  turning  somersaults.  The  flagella  are  long  and  wavy  and 
grow  out  from  the  whole  surface  of  the  bacillus.  The  isolation  of 
tjie  bacilli  and  the  proper  staining  of  their  flagefla  is  a  beautiful 
bactei'ilogical  test  of  skill,  and  when  successfully  achieved  fits  the 
student  for  the  most  complicated  work.  Plate  61  is  photographed 
from  a  slide  prepared  from  an  agar  culture  and  the  flagella  are 
stained  by  the  author's  rnethod. 

The  typhoid  bacillus  stains  well  with  carbol  fuchsin  and  gentian 
violet,  but  with  other  dyes  the  rods  do  not  stain  as  readily  as  many 
other  germs.  Gram's  staining  method  is  negative.  The  bacilli 
grow  in  clumps  in  the  tissues  and  spleen  and  when  stained  thus 
should  remain  for  one  day  in  Loeflier's  methylene  blue  or  Ziehl's 
carbol  fuchsin  and  then  washed  in  distilled  water.  Methylene  blue 
fades  after  a  time,  so  the  carbol  fuchsin  or  gentian  violet  is  pre- 
ferable. 

The  typhoid  bacihus  is  aerobic,  and  does  not  liquify  gelatin. 
It  grows  well  upon  nearly  all  nutrient  media  at  room,  temperature, 
but  most  luxuriantly  at  blood  heat  in  an  incubator.  It  will  grow  as 
an  anaerobe  also  and  thrives  fairly  well  in  the  presence  of  CO2 
(carbonic  acid  gas). 

BOUILLON  CULTURE.— Bouillon  is  clouded,  becoming 
slightly  acid,  and  there  is  a  quantity  of  sediment  formed  from 
which  Brieger  obtained  in  1884  a  ptomaine  which  he  named  Typho- 
toxin  C7  Hi 7  NO2.  This  ptomaine  forms  in  considerable  quantity 
in  a  test  tube  kept  at  98°  F.  for  one  week.  This  ptomaine  is 
strongly  alkaline.  Typhotoxin  produces  salivation,  rapid  respira- 
tion, dilation  of  the  pupils,  diarrhoea  and  death  when  given  to  small 
animals  such  as  guinea  pigs.  The  experiments  have  not  been  tried 
on  man,  but  Brieger  believes  that  the  specific  action  of  the  typhoid 
bacillus  in  tpyhoid  fever  is  due  to  the  production  of  the  ptomaine. 

MILK  CULTURE.— The  bacillus  grows  well  in  milk  and 
forms  some  acid,  but  does  not  cause  coagulation,  hence  its  presence 
is  not  easily  detected.     The  ptomaine  is  formed,  however,  and  has 


184  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

Bacillus  Typhosus,  Eberth,  Koch  (1880) 

BACILLUS    OF    TYPHOID    FEVER;     KOCH-EBERTH's    BACILLUS. 

Origin. — It  was  first  obtained  from  the  spleen  and  lymphatic  glands  of 
typhoid  fever  cadavers.  It  is  present  in  the  blood  in  small  numbers;  also 
in  the  feces  and  urin  of  typhoid  patients. 

Form. — Rather  large  rods,  two  to  three  times  as  long  as  wide,  with 
rounded  ends.  The  length  depends  upon  the  medium  on  which  it  grows. 
On  agar  the  rods  are  short;  on  potato  long  threads  appear.  Involution 
forms. 

Motility. — Actively  motile,  with  numerous  lateral  flagella;  fine  giant 
whips.  It  may  show  very  little  or  no  motion  on  prolonged  artificial  cul- 
ture. 

Sporulation. — Round  or  oval  terminal  bodies  occur  in  potato  and  agar 
cultures  grown  in  the  incubator  for  several  days.  They  will  not  double 
stain,  and  the  bacilli  which  contain  them  are  very  susceptible  to  heat. 
These  are  not  true  spores,  but  little  masses  of  condensed  protoplasm. 
The  bacilli  are  very  resistant  to  dessication,  and  may  retain  their  vitality 
for  months. 

Anilin  Dyes. — Do  not  stain  well.  Carbolic  fuchsin  stains  very  well. 
Gram's  method  will  not  stain. 

Growth. — Is  less  rapid  than  that  of  the  Colon  Bacillus.  It  grows 
slowly  at  i6-i8°. 

Plates. — On  gelatin  plates  the  deep  colonies  are  small,  round  or  oval, 
yellowish  and  finely  granular,  with  sharp  border.  They  sometimes  show 
a  dark  portion  or  ring  in  the  center.  A  protuberance  may  frequently  be 
seen  on  the  border,  which  is  surrounded  at  times  with  delicate  fibrils. 
The  surface  colonies  form  a  spreading,  almost  transparent  film,  marked 
with  delicate,  branching  lines,  and  having  an  irregular,  wavy  border. 
There  is  no  liquefaction. 

Stab  Culture. — Growth  is  abundant  along  the  entire  line  of  inocula- 
tion; is  especially  so  on  the  surface,  spreading  there  as  a  thin,  grayish 
white  covering.     Acids  are  produced  which  cloud  the  gelatin. 

Streak  Culture. — On  agar  and  on  blood-serum  a  white,  moist  growth 
is  formed.  On  potato,  a  moist,  invisible  layer  is  formed.  On  alkaline 
potato  the  growth  is  yellowish;  not  characteristic. 

Bouillon. — Is  slightly  cloudy,  not  so  much  so  as  with  the  Colon  ba- 
cillus. There  is  very  little  deposit;  scarcely  any  ring  or  film.  Remains 
clouded  for  a  long  time.  It  will  not  grow  in  bouillon  containing  20  c.  c. 
of  N  HCL  or  50  c.  c.  of  N  NaOH  per  liter,  unlike  the  Colon  bacillus. 
No  indol  is  produced.     In  Uschinsky's  medium  there  is  no  growth. 

Milk. — Is  not  coagulated.  No  gas  is  formed  in  glucose  media;  no 
acid  in  lactose  media. 

Oxygen  Requirements. — It  is  a  facultative  anaerobe. 

Temperature. — Grows  best  at  37°  C. ;  also  grows  well  at  ordinary 
temperature.     Is  killed  by  exposure  to  moist  heat  of  60°  C. 

Aerogenesis. — No  acid  or  gas  production  on  lactose  media. 

Behavior  to  Gelatin. — Does  not  liquefy. 

Immunity. — Injections  of  dead  or  living  cultures  yield  an  anti-infecti- 
ous serum;  injections  of  the  toxin  yield  an  anti-toxic  serum.  The  serum 
in  the  former  case  will  give  Pfeiffer's  reaction  with  the  Eberth,  but  not 
with  the   Colon   bacillus. 

Pathogenesis. — Rabbits  are  usually  killed  by  intravenous  injections. 
It  is  usually  fatal  to  guinea-pigs  when  injected  into  the  duodenum  or  the 
peritoneal  cavity  or  when  introduced  into  the  previously  alkalized  stomach. 
Guinea-pigs  are  killed  bp  subcutaneous  injections  also.  Abscesses  are  pro- 
duced in  dogs  and  rabbits  by  the  same  method  of  infection.  It  may  pro- 
duce abscesses  in  man.  Cultures  killed  with  chloroform  or  by  heating  for 
one  hour  at  54°  are  fatal  to  guinea-pigs  in  doses  of  3-4  m.  g.  per  100  g. 
body  weight. 

Infection. — Takes  place  commonly  through  the  mouth  by  means  of 
water,  food,  soiled  articles,  etc.  It  may  be  transmitted  through  the  air  as 
fine  dust.     Carried  by  flies  and  other  insects. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS. 


185 


Plate  61.     Typhoid  Bacillus  Flagellated 

Magnified  1000  diameters 


wr^  - 


€ 


Plate  62.     Typhoid  Bacillus,  showing  Agglutination 

Magnified  500  diameters. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  187 

been  the  cause  of  severe  poisoning  I  have  no  doubt.  Milk  is  a  great 
carrier  of  the  disease  and  manv  epidemics  have  been,  traced  to 
it  The  contamination  is^usually  made  through  the  water  u^edjn 
rinsing  the  pails,  especially  if  the  water  is  obtained  from  wells  or 
springs  where  the  bacilli  have  found  entrance.  Many  farm  wells 
are  close  to  closets  and  cesspools  and  become  contaminated  from 
the  faecal  matter  of  typhoid  patients.  Epidemics  have  been  traced 
directly  to  this  source  and  there  are  official  records  of  a  number.  In 
1870  Ballard  investigated  the  epidemic  in  Islington,  where  167  peo- 
ple contracted  the  disease,  and  the  investigation  led  to  the  discovery 
that  the  milk  used  by  these  people  was  obtained  from  a  farm  where 
the  well  was  contaminated  by  rat  holes  connecting  with  the  closet. 
The  farmer  had  a  case  of  typhoid  fever  and  the  well  water  was 
usedjto.diise  -the  pails. 

The  fever  broke  out  in  the  prisons  at  Strasburg  in  1890,  and 
the  disease  was  traced  to  the  milk  supply,  which  came  from  a  place 
where  the  fever  was  epidemic.  Rowland,  in  1892,  found  the  living 
bacteria  in  what  is  known  as  ''Dahi,"  which  is  an  Indian  milk 
comestible. 

Since  milk  is  one  of  the  principal  ingredients  of  so  many  fine 
food  products,  especially  of  the  cream  soups,  it  is  perhaps  wise  to 
advise  the  use  of  "Pasteurized"  milk,  for  this  method  destroys  all 
such  germs  as  the  Typhoid  bacillus  long  before  they  have  oppor- 
tunity to  multiply  and  form  ptomaines.  The  great  danger  from 
using _ravv  milk  lies  in  the  possible  contamination  by  disease  germs, 
and  while  these  will  be  destroyed  in  the  sterilizing  process,  the  poi- 
son still  remains  in  certain  quantities,  and  may  cause  sickness  vary- 
ing in  violence  according  to  the  amount  of  poison  present.  Per- 
haps the  amount  of  poison  will  be  so  slight  as  to  cause  no  appre- 
hension, yet  the  food  product  will  not  give  satisfaction. 

POTATO  CULTURE.— A  characteristic  growth  of  the 
typhoid  bacillus  when  planted  on  sterilized  potato;  it  is  almost  in- 
visible and  threads  are  formed  which  have  a  beautiful  serpentine 
motion.  The  potato  is  generally  slightly  acid  and  this  is  favorable 
for  a  typical  growth. 

GELATIN  PLATE  CULTURE.— The  surface  colonies  are 
at  first  small  and  yellowish,  punctiformed,  becoming  round  and 
slightly  notched  and  shining.  The  periphery  is  clear  and  trans- 
parent, slightly  gray;  the  centers  are  opaque  and  slightly  elevated. 
When  magnified  about  seventy-five  times  young  colonies  are  color- 
less and  smooth  bordered;  later  lines  are  visible  like  bands  ex- 
tending from  the  center;  these  gradually  deepen  like  folds  and 
look  like  hen  tracks.  The  colony  has  a  golden  yellow  color  and 
is  very  pretty.  The  deep  colonies  are  whetstone  in  shape  and  yel- 
low, with  smooth  borders  and  slightly  gray. 


188  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

AGAR  CULTURE. — The  surface  colonies  are  irregularly 
round,  smooth  bordered,  gray  and  shining,  and  when  magnified  ap- 
pears bright  yellow  in  color,  becoming  darker  towards  the  center 
with  transparent  edges.  Dark  irregular  lines  run  out  from  the  cen- 
ter and  give  the  colony  a  beautiful  appearance.  The  deep  colonies 
are  yellow  and  finely  granular ;  they  are  opaque,  whetstone  shaped, 
looking  something  like  an  almond.  The  agar  streak  is  even  border- 
ed, slightly  elevated  and  slightly  gray,  wath  a  lustrous  appearance. 
After  a  time  the  color  changes  to  yellow. 

The  study  of  this  bacillus  in  cultures  is  most  interesting  and 
instructive  and  if  care  is  exercised  there  need  be  no  fear  in  cul- 
tivating and  handling  it. .  There  are  so  many  points  of  interest  con- 
'  nected  with  its  life,  its  manner  of  growth  and  its  behavior  under 
i  certain  conditions,  that  the  study  of  its  biological  characteristics 
will  enable  the  student  to  intelligently  investigate  any  other  or- 
ganism. 

Typhoid  bacilli  produce  a  poison  which  interferes  with  their 
reproductive  power,  so  that  cultures  will  cease  growing  after  a  time 
and  the  bacilli  will  not  be  as  actively  motile  as  when  planted  in 
fresh  nutrient  media.  When  growing  in  the  human  body  the  poison 
is  carried  away  in  the  blood  and  it  is  possible  to  determine  quite 
early  if  the  patient  is  attacked  by  the  fever.  The  test  is  made 
with  the  serum  from  the  blood  and  is  called  the  agglutination 
test,  which  may  be  described  as  follows :  A  homogeneous  sus- 
pension of  the  bacilli  is  made  first.  This  is  done  by  taking  a  plati- 
num loop  full  of  the  germs  from  a  culture  about  one  day  old,  which 
has  grown  on  hard  agar;  the  germs  are  loosened  from  one  an- 
other by  rubbing  them  against  the  side  of  a  test  tube  containing 
I  c.c.  of  bouillon.  When  there  is  a  perfect  separation  and  even 
distribution  the  mixture  is  termed  a  homogeneous  suspension,  and 
a  small  quantity  must  be  examined  under  the  microscope  with  a 
magnification  of  500  diameters  to  make  sure  that  there  are  no 
clumps,  and  that  all  the  bacilli  are  actively  motile.  This  being 
ascertained,  different  dilutions  are  made  of  the  blood  serum,  and 
each  dilution  is  inoculated  with  typhoid  bacilli.  This  is  done  on  a 
cover-glass  which  is  then  inverted  over  a  cell  in  a  hollow-ground 
slide  and  sealed  to  avoid  evaporation.  The  hanging  drop  is  then 
placed  in  the  incubator  for  various  lengths  of  time,  and  occasional- 
ly removed  and  examined  under  the  microscope  to  ascertain  if 
the  bacilli  have  gathered  in  bunches.  If  the  blood  has  been  taken 
from  a  typhoid  patient,  the  agglutination  is  almost  sure  to  take 
place  even  in  weak  dilutions.  A  positive  aggultination  is  fairh?- 
conclusive  evidence  of  enteric  fever.  See  Plate  62. 
I  Persons  who  have  had  typhoid  fever  remain  immune  for  a 

considerable  time,  and  in  some  cases  for  life.     Blood  from  such 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  189 

persons  sometimes  gives  a  similar  reaction  as  the  blood  from  a 
typhoid  fever  patient,  but  not  quite  so  marked,  especially  in  the 
great  dilutions. 

The  examination  of  water  to  determine  the  presence  of  typhoid 
is  quite  difficult,  because  there  is  a  class  of  bacteria  called  Coli 
commune  (of  which  there  are  a  number  of  species),  which  closely 
resemble  the  true  typhoid  bacilli.  These  species  are  found  in  the 
faeces  of  healthy  persons  and  water  is  usually  condemned  as  unfit/ 
for  drinking  purposes,  when  any  of  these  are  found,  because  it  in- 
dicates that  it  is  contaminated  with  sewage. 

The  biological  characteristics  of  the  typhoid  bacillus  may  be 
thus  summed  up :  It  is  aerobic  and  facultative  anaerobic,  clouds 
bouillon,  does  not  coagulate  milk,  and  the  reaction  is  amphoteric, 
does  not  form  spores,  is  not  chromogenic,  produces  sulphuretted 
hydrogen  in  abundance,  ordinarily  does  not  produce  indol,  produces 
some  acid  in  grape-sugar-bouillon,  produces  no  gas  in  sugar  agar 
and  grows  fairly  well  in  an  atmosphere  of  carbonic  acid  gas.  It 
produces  a  ptomaine  which  is  a  powerful  poison.  The  study  of  this 
organism  is  most  interesting  to  the  food  chemist  and  investigator. 

Typhoid  is  commonly  epidemic,  and  it  is  no  doubt  carried 
from  one  location  to  another  in  food  and  water,  which  gives  it 
a  place  in  the  catalog  of  dangerous  bacteria  associated  with  food 
spoilage. 

CHOLERA  BACirxUS. 

The  germ  which  produces  Asiatic  cholera  is  called  by  the  fol- 
lowing names :  Comma  Bacillus,  Vibrio  cholera,  Spirillum  cholera 
and  "Bacille  vir  gule"  (French).  The  name  comma  bacillus  was 
given  to  it  on  account  of  the  bodies  often  seen  at  the  end  of  the 
germs,  which  are  incorrectly  described  by  Huppe  as  arthrospores. 
The  germination  of  these  bodies  has  not  been  positively  observed, 
but  they  cause  the  germ  to  look  like  a  comma  (,)  hence  the  name. 

It  is  seldom  that  this  terrible  foe  of  man  gets  a  strong  hold 
in  America,  yet  there  have  been  some  severe  epidemics  which  car- 
ried whole  families  and  communities  out  of  existence  in  a  few  days. 
In  various  parts  of  Asia  it  is  epidemic  nearly  all  the  time.  It  is 
said  that  in  Saigon,  Asia,  there  are  always  a  few  cases,  and  at 
times  it  spreads,  carrying  death  to  thousands. 

Not  until  1884  was  it  known  positively  just  what  was  the 
agent  of  this  dreaded  disease.  Dr.  Koch  of  Berlin  made  the  dis- 
covery of  the  germ  and  showed  how  it  w^as  carried  in  water  and  in 
food  from  one  place  to  another.  Dr.  Koch  carried  on  his  researches 
in  Egypt  and  India,  and  other  eminent  bacteriologists,  both  from 
Europe  and  America,  have  made  searching  investigations  of  the 
micro-organism  and  have   studied  its  biological  characteristics  to 


190  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

such  an  extent  that  the  disease  is  now  combated  with  more  success 
than  formerly  when  the  true  cause  was  shrouded  in  mystery. 

The  disease  makes  its  appearance  in  every  country  occasional- 
ly, the  specific  organism  being  carried  from  infected  districts  by 
travelers,  in  articles  of  food  and  clothing,  etc.  The  organism  is 
one  of  the  few  which  produces  several  ptomaines  and  toxic  poisQUS, 
some  of  which  are  very  dangerous.  The  specific  action  of  these  poi- 
sons are  varied,  and  violent  sickness  and  even  death  may  result 
from  them  if  taken  in  food  which  has  been  contaminated.  Of 
course  there  is  danger  only  when  the  disease  is  rife  in  certain  lo- 
calities, and  when  food  stuff  is  obtained  from  such  places. 


Plate   63 


The  Cholera  spirillum  is  a  curved  rod  measuring  from  0.8  to 
2/x  in  length  and  0.3  to  o.4/>t  broad,  the  ends  being  rarely  in  the  same 
plane,  so  that  when  several  are  united  they  resemble  a  corkscrew. 
When  seen  singly  they  resemble  a  comma  and  when  seen  in  pairs 
may  form  the  letter  (S)  or  the  letter  (O).  The  (S)  forms  are 
quite  common  where  the  growth  is  rapid.  The  long  corkscrew- 
forms  are  seen  generally  in  hanging  drop  cultures  growing  in  favor- 
able temperatures  or  conditions.  Old  cultures  assume  varied  forms, 
bearing  little   resemblance   to  young   cultures.     Involution   forms 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  191 

with  spherical  bodies  are  produced,  which  are  thought  to  be  spores 
belonging  to  the  so-called  anthrospore  type  of  spore  formation,  but 
no  one  has  observed  the  germination  of  these  bodies.  It  is  a  motile 
organism  having  a  single  terminal  flagellum;  sometimes  two  flagella. 

Milk  is  a  good  medium  for  growth  and  is  coagulated  with  the 
production  of  lactic  acid. 

Indol  is  formed  abundantly  in  nutrient  media  containing  pep- 
tone or  albumen.  The  presence  of  indol  in  cultures  may  be  demon- 
strated by  adding  a  minute  quantity  of  muriatic  or  sulphuric  acid 
to  the  medium,  when  a  rose-red  color  will  make  its  appearance  and 
is  known  as  the  nitrose  indol  reaction.  In  all  cultures  containing' 
albumen  indol  is  formed  first  and  then  the  nitrates  are  converted  into 
nitrites.  This  is  also  true  of  at  least  two  other  species  of  bacteria. 
All  cultures  of  the  cholera  have  a  disagreeable,  sickening  odor,  but 
these  are  not  specially  characteristic. 


%  * 


^:^-^. 


1 


%\ 


Plate  64.     Bacillus  Coli  Communis,  showing  Flagella 

Stained  by  the  author.       Magnified  1,000  diameters. 

Media  containing  either  milk-grape  or  cane  sugar  favor  the 
production  of  lactic  acid,  which  is  dextrorotatory. 

A  beautiful  chemical  reaction  is  seen  when  cholera  is  grown  in 
a  test  tube  containing  litmus  milk ;  a  pale  blue  pellicle  is  formed  on 
the  top,  under  which  is  a  stratum  of  red,  while  the  lower  portion  will 
be  entirely  decolorized. 

Sulphuretted  hydrogen  (HgS)  is  formed  abundantly  in  peptone 
bouillon  and  also  in  sterilized  egg  albumen.  Cholera  germs  are 
not  very  resistant  to  unfavorable  conditions.  They  are  killed  in 
water  heated  to  130  degrees  F.,  and  when  frozen  they  die  within  a 


192  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


Bacillus  Coli  Communis^  Kscherich  (1886) 

BACTERIUM    COLI    COMMUNE/    THE    COLON    BACILLUS,"    EMMERICH's    BACILLUS,* 

B.    NEAPOLITANUS. 

Origin. — Found  in  the  intestinal  contents  of  man  and  animals,  es- 
pecially in  the  colon;  also  occurs  in  the  discharges  of  healthy  infants  and 
in  summer  diarrhoea.  It  frequently  accompanies  the  Comma  Bacillus  in 
the  discharges  of  Asiatic  cholera.  It  resembles  in  many  respects  the  ty- 
phoid fever  bacillus. 

Form. — Short,  narrow  rods,  varying  in  length  from  coccus-like  forms 
to  rods  four  to  six  times  as  long  as  wide.  Usually  found  in  pairs,  may 
form  threads. 

Motility. — Depends  upon  the  medium,  age  and  temperature.  It  has 
diffuse  flagella  and  giant  whips. 

Spondation. — Has  not  been  observed. 

Anilin  Dyes. — Stain  readily.  Gram's  method  will  not  stain.  Bi-polar 
stain  frequently  occurs ;  also  plasmolytic  changes,  as  in  potato  cultures. 

Groivth. — More  rapid  than  that  of  typhoid  bacillus. 

Plates. — On  gelatin  plates  dull-white  surface  colonies,  with  irregular 
border  and  markings  in  the  outer  zone,  are  formed.  These  colonies  are 
fiat,  spreading  and  aniso-diametric.  The  deep  colonies  are  round  or  oval 
in  form  and  of  a  yellowish  color;  they  are  frequently  divided,  forming 
lobulated  masses.  The  round  colonies  have  usually  a  yellow  granular  cen- 
ter surrounded  by  a  colorless  homogeneous  ring.  Does  not  liquefy. 
Strong  odor  of  indol  and  amine.  Owing  to  the  ammoniacal  reaction,  the 
gelatin  deposits  a  cloudy  precipitate  between  the  colonies  and  along  any 
scratches  that  may  occur  on  the  glass  plate.  These  characteristics  differ- 
entiate it  from  the  typhoid  bacillus. 

Stab  culture. — Along  the  line  of  iroculation  the  growth  is  rather  en- 
ergetic.    On  the  surface  a  white  film  with  wavy  border  is  formed. 

Streak  Culture. — On  agar,  a  moist,  white,  spreading  growth  is  formed; 
old  cultures  sometimes  show  needle-shaped  crystals.  On  potato,  an  abund- 
ant, yellowish,   moist   slowly  spreading  growth   is   formed. 

Milk. — Coagulates  in  one  or  two  days ;  sometimes  a  week  or  more  may 
be  required. 

Bouillon  becomes  very  cloudy,  with  heavy  sediment;  at  the  surface  a 
thick  ring  may  adhere  to  the  glass ;  a  broken  pellicle  may  form.  Marked 
indol  reaction. 

Oxygen  Requirements. — It  is  a  facultative  anaerobe. 

Temperature. — Grows  best  at  about  zy""  C,  but  will  grow  well  at  or- 
dinary temperature. 

Behavior  to   Gelatin. — Gelatin  is  not  liquefied. 

Aerogenesis. — When  glucose  is  present  carbonic  acid  and  hydrogen 
are  produced  abundantly.  Acid  and  gas  may  be  formed  in  lactose  media 
— unlike  the  typhoid  bacillus. 

Pathogenesis. — Guinea-pigs  are  very  susceptible ;  rabbits  less  suscep- 
tible, and  mice  are  insusceptible.  Diarrhoea,  collapse  and  death  are  pro- 
duced in  one  to  three  days  by  small  intravenous  injections  or  injections 
into  the  abdominal  cavity.  The  small  intestine  is  hyperemic,  more  or 
less  intensely  inflamed  ;  serous  exudates  may  be  present.  The  bacilli  are 
abundant  in  the  blood,  in  organs  and  on  the  peritoneum.  Subcutaneous 
injections  produce  only  a  local  abscess  usually;  is  not  usually  fatal. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  193 

few  days.  Drying  kills  them  in  a  few  hours.  Weak  antiseptics 
destroy  them.  They  require  frequent  transplanting  in  favorable 
nutrient  media  to  keep  them  for  any  long  period. 

The  bacterial  poisons,  forrned  by  the  cholera  germ  are  very 
powerful.  Old  bouillon  cultures,  when  filtered  through  the  Cham- 
berland  filter  has  all  germs  removed,  but  the  poison  in  solution  kills 
small  animals,  such  as  rabbits,  mice,  guinea  pigs,  etc. 

Putrescin  and  cadaverin  are  two  ptomaines  extracted  by  Brie- 
ger  from  cholera,  but  are  not  very  poisonous.  Methyl-guanidin  is 
another,  but  is  very  poisonous,  causing  muscular  tremors  and  death. 
"Toxopepton"  was  obtained  by  Petri  as  a  poisonous  proteid  which 
killed  guinea  pigs  in  a  few  hours  in  doses  of  36  grams  per  kilogram 
weight. 


Plate  65.     Bacillus  Coli  Communis 

Magnified  1,000  diameters. 

A  substance  insoluble  in  water  and  acids,  but  soluble  in  alkalis 
and  ether  is  obtained  by  a  method  discovered  by  Winter  and  Lesage. 
When  evaporated  from  the  extract,  it  is  oily  and  becomes  yellow  like 
fat  on  cooling.  Small  doses  are  fatal  in  a  short  time  when  fed  to 
small  animals. 

BACILLUS   COLI   COMMUNIS   OR   COLON   BACILLUS. 

This  very  common  bacillus  is  not  a  single  species,  but  a  family 
comprising  a  number  of  species  very  closely  resembling  one  another 
and  differentiated  only  by  most  careful  study.  It  is  a  question 
whether  there  are  distinct  species  or  whether  the  one  species  changes 
in  its  morphological  and  biological  character  under  certain  condi- 
tions, thus  causing  confusion.  Various  textbooks  attempt  a  separa- 
tion of  species  according  to  their  different  pathogenic  power,  but 


194  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

in  my  own  researches  I.  have  been  unable  to  make  a  clear  distinction 
between  any  germs  of  this  family.  The  Coli  communis  is  always 
present  in  intestines  of  healthy  man  and  various  animals,  and  is 
nearly  always  found  associated  with  other  bacteria  in  a  number  of 
diseases,  such  as  suppurative  processes  in  the  internal  organs,  in- 
fectious enteritis,  ulcerated  liver,  puerperal  fever,  meningitis,  etc. 

The  bacillus  resembles  the  typhoid  bacillus  so  closely  in  its 
form,  size  and  its  growth  on  various  culture  media  as  to  make  its 
differentiation  a  nice  bacteriological  problem. 

The  differences  may  be  stated  as  follows :  It  is  not  so  actively 
motile  as  typhoid,  has  fewer  and  shorter  flagella,  it  develops  more 
luxuriantly  on  all  media,  and  the  growth  on  potato  is  visible,  while 
that  of  typhoid  is  not.  It  coagulates  milk,  giving  marked  acid 
reaction,  while  typhoid  does  not  and  the  acid  reaction  is  only  slight. 
It  forms  considerable  gas  in  media  containing  glucose,  lactose  and 
saccharose.  Colonies  are  pink  on  (alkaline)  agar  and  gelatine 
media  containing  lactose  and  litmus  tincture,  while  those  of  Typhoid 
are  pale  blue. 

It  produces  indol  (in  peptone  solutions)  more  freely  than 
typhoid.  Typhoid  as  a  rule  does  not  produce  indol,  but  it  is  some- 
times formed  in  peptone  solutions. 

Agglutination  test  is  generally  negative.  Pfeiffer's  serum  re- 
action with  typhoid  blood  serum  as  described  under  typhoid  is  nega- 
tive with  the  Coli  communis. 

Tyrotoxicon  is  supposed  to  be  a  poison  formed  by  this  microbe, 
although  the  evidence  is  not  positive.  In  1886  this  poison  was  first 
discovered  in  milk  which  had  poisoned  a  number  of  persons  at  Long 
Branch.  The  milk  had  been  exposed  to  unusual  conditions,  favor- 
ing the  growth  of  the  Colon  bacillus  probably.  V.aughan  reported 
an  interesting  case  of  poison  from  tyrotoxicon,  known  as  the  Milan 
case.  The  symptoms  were  rapid  pulse,  breathing  rapid,  burning 
sensation  in  the  throat  and  stomach,  abdomen  retracted  and  severe 
throbbing  in  the  abdomen.  The  contamination  of  milk  from  germs 
which  were  present  in  decomposing  matter  under  the  floor  was  found 
to  be  the  cause.  Vaughan  and  Novy  found  the  poison  in  numerous 
samples  of  poisonous  ice  cream  and  custard.  Novy  says  that  ''Un- 
doubtedly there  are  many  forms  of  the  Colon  bacillus  which  fre- 
quently find  their  way  into  milk  and,  on  account  of  the  toxins  con- 
tained within  their  cells,  they  render  this  and  various  other  foods, 
of  which  milk  is  a  constituent,  more  or  less  poisonous."  The  potas- 
sium compound  of  tyrotoxicon  is  not  decomposed  in  a  temperature 
under  265  degrees  F.,  so  that  foods  containing  milk  and  cheese 
which  have  been  exposed  in  any  way  to  human  or  animal  excreta  or 
to  contaminated  water  are  liable  to  have  this  poison  formed  by  the 
Bacillus   coli   communis.      The  poison   is   present   in   the   human 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  195 

faeces,  but  ordinarily  passes  away  without  any  serious  results,  as  it 
is  formed  past  the  danger  line. 

Tyrotoxicon  may  be  formed  by  other  agents,  but  the  accurate 
knowledge  of  its  origin  is  not  yet  thoroughly  investigated.  It  is 
a  powerful  poison  and  many  fatalities  have  followed  where  food 
containing  it  has  been  eaten.  It  is  generally  found  in  milk,  ice 
cream  and  cheese,  from  which  it  derives  its  nanie. 

TETANUS. 

Tetanus  or  lockjaw  is  a  disease  produced  in  man  and  nearly  all 
domestic  animals  by  a  widespread  germ  found  in  garden  soil,  ma- 
nure heaps  and  saltpeter  beds.  The  horse  is  the  most  susceptible 
domestic  animal,  but  cows,  sheep,  pigs  and  goats  are  sometimes  at- 
tacked. Man  is  very  susceptible  to  this  disease,  which  is  considered 
to  be  one  of  the  most  dangerous  and  deadly. 

The  germ  produces  several  very  powerful  ptomaines,  which 
have  been  isolated  by  Brieger  in  crystalline  forms ;  Tetanine,  which 
decomposes  in  acid  and  remains  unaltered  in  alkaline  solutions,  wilf 
in  itself  produce  lockjaw  when  injected  into  the  tissues  of  animals; 
tetanoxin,  which  produces  tremors  and  paralysis,  followed  by  con- 
vulsions; tetanotoxin,  which  induces  lockjaw,  accompanied  by  a  flow 
of  tears  and  saliva;  and  spasmotoxin,  which  produces  spasms  and 
convulsions.  Late  investigators  have  formed  the  opinion  that  the 
crystalline  substances  obtained  by  Brieger  owed  their  poisonous 
properties  to  the  toxin  of  tetanus  and  that  they  were  not  of  them- 
selves poisons. 

The  flesh  of  animals  suffering  from  disease  is  apt  to  contain 
such  elements,  and  if  such  flesh  should  be  used  in  the  preparation  of 
food  products,  either  in  soups,  extracts  or  canned  meats,  the  direful 
results  may  be  far  reaching.  Packers  who  use  meats  can  thus  un^ 
derstand  how  necessary  it  is  to  be  careful  in  their  selection;  any  un- 
natural appearances  should  be  a  suflicient  reason  for  rejecting  any 
lot  of  meat  which  they  ma}-  be  using. 

The  poison  of  the  tetanus  germ  has  been  used  by  natives  of 
the  New  Hebrides,  according  to  Ledantec,  on  arrowheads  made  of 
human  bones,  which  they  first  cover  with  resin  and  smear  with  the 
slime  found  in  swamps;  the  slime  no  doubt  contains  the  tetanus 
bacilli  in  large  numbers  and  even  a  slight  wound  from  such  weapons 
of  warfare  would  prove  fatal. 

The  tetanus  bacillus  when  magnified  one  thousand  diameters  is 
seen  to  be  slender,  with  a  large  spore  in  the  end  of  the  rod  which 
does  not  readily  take  a  stain.  In  measures  from  3  to  5  />t  in  length 
and  0.3  to  0.5  /*  in  width.  In  cultures  it  is  seen  to  grow  in  threads 
and  often  appears  without  the  spore,  but  usually  the  spore  is  present 
in  single  rods  and  gives  the  germ  the  appearance  of  a  nail,  from 


196  CANNING  AND  PRESERVING  OF  P^OOD  PRODUCTS. 

Bacillus  Tetani,  Nicolaier  (1884) 

TETANUS,  lock-jaw;    wundstakrkrampf    (germ.);   tetanos.    (fr.) 

Origin. — It  is  found  in  animals  that  die  of  tetanus  after  inoculation 
with  earth ;  in  traumatic  tetanus  of  man  and  animals ;  in  head  tetanus ; 
tetanus  of  new-born ;  is  present  in  the  intestines. 

Form. — Large,  narrow  rods,  having  rounded  ends ;  may  form  threads. 

Motility. — It  is   motile.     Many   curly   flagella,   also   giant  whips. 

Sponilation. — Spores  are  formed  rapidly  at  37°.  Terminal  spores 
are  formed,  with  enlargement-drum-sticks. 

Anilin  Dyes. — Stain   readily.     Gram's  method  may  be  used. 

Growth. — Slow. 

Plates. — Colonies  develop  in  gelatin  at  ordinary  temperature  in  four 
to  seven  days ;  these  resemble  those  of  the  Hay  bacillus.  The  gelatin 
slowly  liquefies,  and  gas  is  produced.  On  agar  plates  the  colonies  have 
the  appearance  of  faint  clouds ;  when  examined  under  the  microscope  these 
are  seen  to  be  oval,  partially  surrounded  by  a  whorl  of  extremely  fine 
threads. 

Stab  Culture. — No  growth  at  the  upper  part  of  the  tube.  In  glucose 
gelatin  tubes  cultures  show  a  cloudy  growth  along  the  line  of  inoculation, 
which  radiates  outward  into  the  gelatin,  resembling  that  of  the  Root  ba- 
cillus. The  gelatin  is  eventually  liquefied.  Gas  bubbles  are  present.  In 
glucose  agar  at  37°  the  growth  is  sometimes  indistinct,  showing  radia- 
tions. 

Streak  Culture. — On  glucose  agar  growth  is  rapid  and  practically  in- 
visible. 

Bouillon. — It  becomes  diflfusely  cloudy  at  37°,  but  after  several  days 
the  growth  settles  to  the  bottom  in  the  form  of  a  scarcely  visible  sediment. 

Glucose  Gelatin,  colored  with  litmus. — Becomes  permanently  lique- 
fied at  37°,  a  very  small  sediment  is  formed.  The  culture  remains  blue, 
thus  showing  that  there  is  no  acid  formation. 

Milk. — Grows  well  in  milk,  but  produces  no  change.  Starch  is  not 
inverted.     On  potato,  the  growth  is  invisible. 

Oxygen  Requirements. — It  is  an  obligative  anaerobe,  growing  in  va- 
cuum, hydrogen,  carbonic  acid  and  nitrogen. 

Temperature. — Grows  best  at  about  38°  C.  Will  not  grow  below  16°  C. 

Behavior  to  Gelatin. — Liquefies. 

Aerogenesis. — Produces  gas;   has  disagreeable  odor;   H2S. 

Attenuation. — There   is   a   loss   of  virulence  by  culture. 

Immunity. — lodin  trichlorid;  thymus  bouillon  cultures;  injection  of 
filtered  cultures ;  of  purified  toxin ;  milk  of  immunized  goat ;  blood-serum 
of  rabbits,  dogs,  sheep,  horses,  which  have  been  artificially  immunized. 
The  tetanus  toxin  is  destroyed  by  the  nucleohiston  from  the  thymus  gland. 

Pathogenesis. — Man,  horse,  sheep,  young  cattle,  goats,  guinea-pigs, 
white  rats  and  white  mice,  are  susceptible.  Dogs  and  rabbits  are  less 
susceptible.  Chickens  and  ducks,  immune.  It  is  not  present  in  the  blood, 
but  occurs  in  small  numbers  at  the  point  of  inoculation ;  may  be  absent 
entirely  at  times.  Products  are  intensely  poisonous.  A  guinea-pig  may 
be  killed  by  0.002  c.  c.  of  a  filtered  bouillon  culture  and  a  dose  of  0.0002  c. 
c.  may  kill  a  mouse.  Disease  cannot  be  produced  by  pure  tetanus  spores. 
Mixed  infection. 

Infection. — Occurs  through  wounds.  The  poisoned  arrows  of  the 
New  Hebrides  contain  tetc<nus  and  malignant  edema  spores. 

Diagnosis. — On  account  of  its  scarcity  and  the  presence  of  other  ae- 
robic and  anaerobic  bacteria,  the  bacillus  is  hard  to  detect.  The  pus  should 
be  taken  from  the  wound  by  means  of  a  sterile  drawn-out  glass  tube 
pipette  and  transferred  to  glucose  litmus  gelatin.  A  loopful  of  this  dilu- 
tion should  then  be  transferred  to  each  of  eight  or  ten  tubes  of  liquefied 
glucose  agar.  These  should  be  poured  into  Petri  dishes  and  developed  in 
hydrogen.  The  characteristic  colony  is  oval,  surrounded  on  one  end  by  a 
whorl   of  threads. 

The  original  glucose  litmus  gelatin  is  developed  at  35°  ;  a  portion  of 
this  is  injected  under  the  skin  of  a  white  mouse  or  a  guinea-pig. 

A  portion  of  the  pus  .should  be  stained  direct,  then  examined  for 
tetanus  bacilli  and  for  the  terminal  spores  (drum-sticks).     (From  Novy.) 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS. 


197 


Plate  66     Bacillus  Tetanus  Flagellated 
Magnified  1,200  diameters. 


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<VV 


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..^^ 


w  J~ 


Plate  67.     Bacillus  Tetanus 

Magnified  X  1,000.  Photomicrogrash  from  Slide  Prepared  by  Author  from  Bouillon.  Stained  with  Carbol 
Fuchsin.  Large  Terminal  Spares  are  shown,  which  give  to  the  Bacilli  the  Appearance  of  Nails  or  Pins.  It  is 
sometimes  called  the  "Nail  Head  Germ." 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  199 

whence  it  received  the  name  of  "the  nail-head  germ."  The  spore 
is  much  greater  in  diameter  than  the  width  of  the  bacillus  and  gives 
it  the  appearance  of  a  pin  or  a  clove  or  an  eyescrew.  Spores  may- 
be seen  in  the  long  threads  at  times. 

The  spores  remain  alive  and  virulent  in  culture  media  for  more 
than  a  year  (in  a  dark  place),  but  are  not  able  to  live  through  a  boil- 
ing temperature  of  212  degrees  F.,  applied  for  ten  minutes.  Five 
per  cent,  phenol  solution  kills  them  in  one  day,  but  if  muriatic  acid 
is  added  the  spores  perish  within  a  couple  of  hours.  The  vitality 
may  be  tested  by  transplanting  after  exposures  to  heat  and  antisep- 
tics. Bichloride  of  mercury  i-iooo  destroys  them  within  three 
hours,  but  when  muriatic  acid  is  added  to  the  mercury  they  perish  in 
less  than  an  hour. 

The  young  bacilli  may  be  stained  for  flagella  and  the  number  is 
surprisingly  large  and  it  is  difficult  to  count  them.  Votteler  claims 
to  have  counted  50  to  100  growing  out  from  the  entire  surface. 
The  bacilli  are  not  actively,  motile  which  is  more  surprising  from 
the  fact  that  other  germs  with  one-fifth  the  number  of  flagella  are 
very  active.  There  is,  however,  a  distinct  spontaneous  motion 
which  may  be  seen  in  the  hanging  drop  cultures. 

Tetanus  bacillus  is  strongly  anaerobic,  even  small  quantities  of 
oxygen  interfere  with  its  growth,  especially  if  it  is  cultivated  from 
the  animal  body  or  wounds  which  have  become  infected.  After 
transplanting  a  number  of  times  in  nutrient  media  the  tetanus  germs 
become  less  susceptible  to  oxygen  and  have  been  cultivated  quite  suc- 
cessfully in  the  presence  of  other  organisms  belonging  to  the  class  of 
aerobes.  When  grown  as  an  aerobe,  pure  cultures  lose  much  of 
lheir__virulence.  This  is  also  true  of  other  anaerobic  bacteria  be- 
longing to  the  pathogenic  classification. 

Bacillus  tetanus  grows  well  at  98  to  100  degrees  F.  and  slowly 
at  room  temperatinx.  At  50  degrees  F.  there  is  no  growth.  When 
the  germs  are  very  virulent  there  is  only  a  moderate  growth,  even 
at  98  degrees  F.,  but  cultures  that  have  been  frequently  transplanted 
grow  most  luxuriantly.  Many  pathogenic  bacteria  seem  to  change 
in  their  nature  and  develop  the  characteristics  of  the  putrefactive 
species  and  lose  much  of  their  virulence  after  repeated  transplanting. 
These  germs  w^hen  inoculated  into  susceptible  animals  become  high- 
ly virulent  again. 

The  cultivation  of  tetanus  in  artificial  media  is  made  regular 
anaerobic  culture  apparatus  by  using  hydrogen  as  an  atmosphere  af- 
ter driving  out  all  oxygen,  but  the  least  expensive  method  is  the  ab- 
sorption of  oxygen  by  pyrogalic  acid  in  the  presence  of  potassium 
hydroxid,  enough  to  make  the  acid  alkaline,  when  it  will  darken, 
first  brown  and  then  black. 


200  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

Animals  which  have  tetanus  wiU  have  the  active  poison 
throughout  the  circulating  system.  The  hlood  and  gland  secretions 
contain  it  in  sufficient  quantities  to  set  up  the  disease  in  other  ani- 
mals which  are  inoculated  with  the  blood  or  pleural  exudes.  Strange 
to  say,  the  tissue  of  diseased  animals  seems  to  have  to  be  devoid  of 
the  poison,  except  at  the  point  where  the  germs  had  gained  entrance 
i  e.,  the  wound  or  seat  of  inoculation.  The  poison  becomes  inert  if 
subjected  to  temperatures  varying  from  150  to  212  P.,  but  if  it  is 
dried  at  ordinary  temperature  first  it  retains  its  virulence  and  with- 
stands much  higher  temperatures. 

When  the  germs  gain  entrance  into  a  living  animal  or  man 
through  a  wound  the  point  of  entrance  will  heal  over  and  appear _to 
be  getting  \vell.  Tins  places  the  tetanus  bacilli  in  an  anaerobicand 
they_soonJbegin  to  multrply,  the  period  of  jncubatioiL J2eing__frpm 
one  to  twenty-five  days.  If  lockjaw  results  after  one  day  there  are 
probably  a  number  of  pus  germs  in  the  wound,  which  use  up  the 
oxygen  from  the  surface  and  place  the  tetanus  bacilli  in  their  favor- 
able anaerobic  condition,  in  which  case  the  sufferer  has  small  chance 
of  recovery.  The  longer  the  period  of  incubation  the  greater  is  the 
chance  for  recovery,  because  the  system  becomes  more  or  less  arm.ed 
against  the  poison  by  gradually  accommodating  itself  to  its  influence. 

The  anti-tetanic  serum  is  prepared  from  the  blood  of  inoculated 
animals  and  has  been  injected  into  the  blood  of  victims  of  tetanus 
with  satisfactory  results.  The  serum  is  known  to  produce  im- 
munity, and  hundreds  of  positive  cures  are  recorded  from  its  use. 

'rhej;e  isjio  doubt  but  that  the  flesh  of  animals  suffering  with 
lockjaw  contains  large  quantities  of  the  toxin  in  the  juices,  and  if 
iused  as  food  either  in  manufacture  of  canned  meats  or  soup  stock, 
/"Wtti  cause  severe  sickness  and  possibly  death.  It  is  certainly  a 
/  dangerous  malady,  from  the  fact  that  an  animal  may  have  the  di- 
sease during  the  period  of  incubation  and  show  no  outward  sign  of 
its  presence.  There  is  always  an  exceedingly  abundant  production 
of  H2S  (sulphuretted  hydrogen)  where  the  germs  are  grow- 
ing and  indol  is  produced,  so  that  infected  food  products  will  show 
signs  of  contamination  if  care  is  exercised  in  inspection. 

BACILI^US   DIPHTHERIAL   C0I.UMEARUM. 

This  is  a  non-motile  organism,  about  2/x  in  length  and  0.5/A 
broad,  having  rounded  ends.  There  is  no  spore  formation,  and  it 
is  aerobic  and  does  not  liquefy  gelatin.  Tlie  flesh  of  chickens  suf- 
fering with  this  disease  presents  a  flabby  appearance  arrd  is  usually 
somewhat  discolored.  Chickens,  game  birds  and  pigeons  are  sus- 
ceptile,  and  it  is  very  contagious  among  them. 

There  are  numerous  cases  of  ptomaine  poisoning  on  record  due 
to  bacteria  which  have  produced  the  poison  in  chicken ;  indeed,  this 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  201 

is  quite  common.  One  case  happened  three  years  ago  in  Aspin- 
vvall,  Pa.,  at  a  chicken  and  waffle  supper.  Fully  twenty  persons 
were  made  violently  ill  from  eating  the  chicken.  One  case  of 
poisoning  from  chicken  soup  came  under  my  notice  during  a  visit  to 
San  Francisco.  In  this  case  the  soup  had  been  canned  and  was 
perfectly  sterilized,  yet  the  ptomaine  remained.  Just  what  organ- 
ism caused  the  trouble  I  do  not  know,  because  T  was  not  in  a  position 
to  make  a  thorough  examination,  but  part  of  the  soup  when  fed  to  a 
dog  caused  the  animal  to  become  violently  sick.  There  is  no  doubt 
but  that_Bacillus  Diptheriae  Columbarum  is  one  organism  _ which 
produces  a  powerful  toxic  poison  and  that  chickens  suffering  with 
dtptheria  have  the  poison  in  sufficient  quantities  to  produce  severe 
cramps  and  nervous  prostration  with  symptoms  of  paralysis  in  per- 
sons who  partake  of  the  cooked  flesh.  There  is  no  doubt  that  such 
Hiseased  poultry  is  sometimes  sold  on  the  market,  and  packers  of 
potted  chicken,  chicken  soup  and  canned  chicken  should  be  extreme- 
ly careful  in  selection.  If  careful  inspection  is  made^  evidence  of 
disease  will  almost  invariably  be  indicated  by  general  appearance 
and  color. 

Bacillus  Diptheria  Vitulorum  is  another  organism  affecting 
calves  and  is  found  in  the  mouth,  lungs  and  intestines.  It  is  usual- 
ly in  filaments,  and  is  several  times  as  long  as  it  measures  in  breadth. 
It  is  non-liquefying  on  calf  blood  serum,  which  seems  to  be  the  only 
medium  on  which  a  culture  can  be  obtained. 

The  flesh  of  a  calf  suffering  from  diptheria  is  not  sound  in 
color,  nor  is  it  firm,  and  the  usual  precautions  will  suflice  to  aid  the 
inspector  in  judging  it. 

There  are  a  number  of  diseases  affecting  animals  and  poultry 
which  are  due  to  pathogenic  bacteria,  but  I  will  merely  mention  a 
few  of  them,  as  our  readers  are  pretty  familiar  with  the  subject  by 
this  time.  Vibrio  Metschnikovii,  which  is  the  organism  producing 
one  kind  of  chicken  cholera.  Bacillus  of  Chicken  Cholera,  Hog 
Cholera  Bacillus,  Anthrax  Bacillus,  and  various  organisms  which 
produce  blood  poisoning. 

It  must  not  be  supposed  by  our  readers  that  meats  and  albumi- 
nous food  materials,  which  contain  poisons  due  to  the  organisms  we 
have  been  describing,  are  constantly  put  on  the  market  and  sold  to 
unsuspecting  packers.  It  happens  only  rarely  that  such  material  is 
used,  and  our  object  has  been  to  furnish  complete  information  on 
this  subject  to  teach  packers  the  necessity  of  careful  inspection,  both  j 
macroscopically  and  microscopically.  Ptomaine  poisonig  from 
canned  goods  is  extremely  rare  in  comparison  with  such  complica- 
tions from  other  sources,  but  we  hope  to  decrease  these  by  fully  de-, 
scribing  the  various  organisms  known  to  produce  poisons  and  by* 
pointing  out  the  danger  in  using  unsound  material. 


202  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

Every  packer  should  take  a  lively  interest  in  this  subject,  be- 
cause cases  of  Ptomaine  poisoning,  although  rare,  are  a  source  of 
considerable  annoyance  to  the  whole  industry.  Unreasonable  bills 
are  introduced  in  the  legislatures  of  various  states  which  cause  the 
packers  trouble.  I  have  referred  in  former  pages  to  the  "Canned 
Goods  Dating  Bills." 

PTOMAINES  AND  TOXINS. 

Ptomaine  Poisoning  and  Its  Bearing  on  the  Pood  Industry. 

The  word  ptomaine  springs  from  the  Greek  word  (ptoma) 
ptoma,  which  is  pronounced  (toma)  and  means  a  dead  body.  This 
name  was  given  to  a  group  of  poisons  obtained  from  cadavers  by 
Selmi,  a  noted  Italian  chemist  and  toxicoligist.  For  many  years 
the  term  was  applied  to  all  bases  which  combined  with  acids  and 
formed  salts  as  a  result  of  bacterial  activity,  and  these  bases  were 
regarded  as  poisons,  but  later  investigations  have  demonstrated  that 
ptomaines  are  not  all  poisons,  in  fact  only  a  few  of  them  may  be 
considered  as  dangerous.  Many  of  the  ptomaines  owe  their  poison- 
ous properties  to  a  more  powerful  poison,  which  is  termed  a  toxin, 
and  this  is  a  product  of  the  putrefactive  and  pathogenic  bacteria, 
many  of  which  we  have  described.  Novy  describes  a  ptomaine  as, 
*'an  organic  chemical  compound,  basic  in  character,  and  formed  by 
the  action  of  bacteria  on  nitrogenous  matter.  On  account  of  their 
basic  properties,  in  which  they  resemble  the  vegetable  alkaloids, 
ptomaines  may  be  called  putrefactive  alkaloids." 

They  are  formed  in  the  putrefactive  processes  on  both  vege- 
table and  animal  matter  of  albuminous  nature  by  the  agency  of  bac- 
teria. When  such  matter  is  attacked  by  bacteria,  the  various  mole- 
cules containing  carbon,  nitrogen,  oxygen  and  hydrogen,  are  upset 
and  new  atomical  relations  are  formed  by  the  cleavage,  in  the  vari- 
ous steps  of  total  dissolution.  The  final  results  of  bacterial  activity 
is  the  fomation  of  carbon  dioxid,  ammonia,  and  water,  and  it  is  be^ 
tween  the  first  and  last  stages  that  the  alkaloids  are  formed. 

In  some  cases  of  food  poisonings,  toxins  have  been  isolated  as 
well  as  ptomaines,  so  we  will  include  both  in  the  discussion  of  this 
subject. 

The  increase  of  food  poisoning  in  recent  years  has  been  de- 
clared by  some  eminent  authorities  to  the  increased  consumption  of 
preserved  foods,  the  claim  being  made  that  inferior  stuff,  which 
would  not  be  purchased  in  the  raw  state  on  account  of  its  appearance 
and  partial  decomposition  is  easily  made  to  look  well  by  skillful 
chefs  and  manufacturers  of  canned  foods,  and  that  these  contain  the 
poisons  elaborated  by  harmful  bacteria,  and  that  these  poisonous 
alkaloids  do  not  lose  their  potency  in  the  cooking  and  sterilizing 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  203 

processes.  Canners  have  been  accused  of  using  partially  decom- 
posed materials,  both  knowingly  and  ignorantly,  and  the  responsi- 
bility for  a  large  number  of  food  poisoning  cases,  has  been  charged 
against  them.  For  the  most  part  ignorance  has  been  charged  be- 
cause they  are  not  familiar  with  the  scientific  principles  of  their  busi- 
ness, and  do  not  realize  the  dangers  lurking  in  decomposing  ma- 
terial, due  to  vital  activity  of  bacteria. 

While  there  may  be  extremely  little  truth  in  these  statements 
and  while  we  must  admit  that  the  canners  and  preservers  of  food 
products  have  been  guilty  of  gross  ignorance,  and  are  not  even  today 
well  informed  on  these  matters,  we  cannot  help  making  the  state- 
ment that  the  charges  are  very  much  overdrawn  and  that  the  ignor- 
ance displayed  by  the  canners  could  hardly  surpass  that  displayed  by 
the  list  of  physicians,  who  are  for  the  most  part  to  blame  for  the 
charges  of  ptomaine  poisoning  against  canned  goods.  In  order  to 
write  intelligently  on  this  subject,  I  have  made  it  a  point  to  question 
a  number  of  physicians  concerning  ptomaines  and  toxic  poisons,  and 
their  answers  showed  that  they  were  as  a  rule  ignorant  of  their 
names  and  origin. 

I  do  not  mean  to  cast  reflections  upon  physicians  in  general; 
many  of  them  are  conscientious  in  their  diagnoses  and  would  not 
place  the  blame  on  canned  goods  without  investigating  the  cause 
carefully.  There  are  others,  however,  who  jump  at  conclusions  and 
furnish  the  press  with  information  Avhich  may  be  absolutely  untrue. 
Inlhis  manner  false  statements  have  been  circulated  throughout  the 
civilized  world  and  the  preserving  industry  has  had  to  bear  the 
brunt  in  many  cases. 

It  is  not  true  that  canners  and  preservers  are  in  the  habit  of 
using  partially  decomposed  material.  It  is  impossible  to  make  fine 
goods  from  anything  but  the  very  best  raw  material,  and  all  reput- 
able firms  are  extremely  careful  in  selecting  the  very  best,  and  their 
contracts  with  farmers  are  strict. 

We  must  admit,  however,  that  there  are  some  packers  who  are 
ignorant  of  the  dangers  of  which  we  are  writing  and  there  may  be 
some  who  are  unscrupulous,  but  the  goods  turned  out  by  these 
manufacturers  are  very  inferior,  often  highly  colored  to  cover  up 
imperfections,  and  the  quality  is  very  poor.  There  have  been,  and 
probably  are  today,  a  few  packers  who  come  under  these  two  classes. 
A  good  Natural  Pure  Food  Lazv  will  be  a  great  blessing  to  the 
whole  industry,  and  will  eliminate  all  goods  artificially  colored,  and 
unnecessarily  preserved  with  antiseptics.  When  this  law  is  made 
effective,  the  honest  and  well  informed  food  preservers  will  enjoy 
a  ready  market  for  all  their  goods,  and  will  not  be  embarrassed  by 
persecutions. 


204  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

When  all,  or  nearly  all,  goods  of  inferior  quality  are  elimin- 
ated, there  will  be  renewed  confidence  in  manufactured  food  pro- 
ducts, and  the  worry  of  putting  up  goods  at  home  will  form  a  part 
of  past  history.  The  superiority  of  manufactured  food  products 
over  home  made  goods  is  conceded  by  the  intelligent  consumers,  for 
the  reason  that  only  men  of  great  skill  are  employed  to  produce 
goods  of  fine  quality,  and  by  the  use  of  improved  machinery  the 
little  imperfections  seen  in  the  home  goods  are  overcome. 

The  progress  now  being  made  in  the  science  of  bacteriology, 
and  the  research  work  in  physiological  chemistry,  are  furnishing 
considerable  literary  material,  which  is  being  published  to  en- 
lighten manufacturers  on  these  subjects.  The  problems  of  spoilage 
are  now  taken  up  carefully,  and  the  various  ptomaines  and  toxins 
are  becoming  known,  also  the  bacteria  which  are  responsible. 

The  isolation  of  ptomaines  and  toxins  requires  great  skill  and 
patience,  and  there  are  only  a  very  few  men  who  are  far  enough 
advanced  to  make  these  analyses,  and  our  readers  will  be  able  to 
judge  of  this  from  the  examples  we  will  give  as  illustrations. 

We  will  not  attempt  in  a  work  of  this  kind  to  give  a  complete 
list  of  all  these  poisons  (and  methods  of  extracting  them),  but  if 
anyone  desires  to  enter  into  the  study  in  a  comprehensive  manner 
we  will  be  glad  to  furnish  material  for  such  research.  Manufac- 
turers who  have  suits  brought  against  them  on  account  of  reported 
ptomaine  poison  found  in  their  goods  need  some  direct  information 
on  the  methods  employed  by  chemists  in  isolating  these  poisons,  in 
order  to  supply  their  lawyers  with  the  necessary  questions  to  be 
asked  the  physicians  who  testify  in  such  cases.  The  methods  de- 
scribed here  will  show  how  complicated  the  analyses  are  and  it  is 
safe  to  say  that  they  will  be  sufficiently  advanced  to  enable  a  good 
attorney  to  overthrow  mere  guesswork  of  many  physicians  who 
testify  in  these  cases.  Not  long  ago  a  certain  well-known  firm  was 
called  upon  to  make  defense  in  suit  for  damages ;  the  parties  claim- 
ing ptomaine  poisoning  wdiere  canned  goods  were  used  at  a  meal, 
after  which  one  member  of  the  family  was  taken  violently  ill. 
Three  doctors  were  called  in,  and  worked  all  night  to  save  the  wo- 
man, and  succeeded,  but  the  family  being  poor,  and  the  doctor's  bills 
large,  a  suit  for  damages  seemed  to  be  a  good  way  to  even  up.  When 
the  case  came  up,  and  the  attorney,  (armed  with  the  chemical  meth- 
ods for  extracting  ptomaines)  asked  the  doctors  the  various  ques- 
tions, the  case  seemed  ridiculous  and  was  thrown  out  of  court.  In 
July,  1903,  when  the  writer  was  in  St.  Paul  attending  the  Conven- 
tion of  State  Food  Commissioners  and  Chemists,  an  article  ap- 
peared in  the  papers  stating  that  a  family  had  been  poisoned  with 
food  containing  a  ptomaine,  and  the  physician  who  attended  the  pa- 
tients was  quoted  as  authority  for  the  statement.     Samples  of  the 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  205 

food  and  some  of  stomach  contents  were  sent  to  the  bacteriologist 
of  St.  Paul  and  the  analysis  proved  it  to  be  a  common  mineral 
poison  and  not  a  ptomaine.  The  cooked  beefsteak  was  found  to 
contain  this  poison.  Hbw  the  poison  happened  to  be  there  no  one 
was  able  to  learn,  but  the  point  I  wish  to  make  is  that  ptomaine 
poisoiis,,are  not  always  responsible. 

These  cases  demonstrate  the  hasty  conclusions  often  reached 
by  doctors.  To  be  sure  they  furnish  sensational  reading,  but  the 
manufacturer  of  foodstuffs  is  put  to  considerable  worry  and  ex- 
pense to  defend  himself  when  suits  are  entered  against  him  for 
damages. 

In  making  examinations  of  suspected  food,  the  samples  should 
be  brought  to  the  laboratory  without  delay  to  lessen  the  change  of 
other  germs  gaining  entrance.  The  germs  present  on  the  inside 
of  the  material  are  probably  the  cause,  and  cultures  are  prepared 
according  to  the  well-known  plate  methods.  Some  of  the  plates 
are  incubated  in  the  anaerobic,  and  others  in  the  ordinary  way,  so 
that  all  the  bacteria  present  may  come  under  the  eye  of  the  analyst. 
There  is  hardly  ever  enough  of  the  suspected  food  to  make  a  chemi- 
cal test  for  a  ptomaine  or  toxin,  because  it  is  impossible  to  extract 
the  minute  quantities  of  these  powerful  poisons  except  from  large 
quantities  of  material.  If  any  appreciable  amount  of  poison  of 
bacterial  origin  could  be  isolated  from  a  small  quantity  of  material, 
it  w^ould  be  so  powerful  as  to  kill  in  a  short  time  all  the  affected 
persons.  One  gram  of  tetanotoxin  is  calculated  to  be  sufficient  to 
kill  4,500  people. 

After  the  germs  have  been  isolated,  those  of  poisonous  char-| 
acter  are  easily  identified,  and  each  species  is  then  tested  on  suchi 
animals  as  mice,  rats,  kittens,  puppies,  rabbits  and  guinea-pigs  by 
feeding,  by  subcutaneous,  inoculation,  by  ultra-peritoneal  inocula- 
tion and  by  intravenous  inoculation.  Various  animals  are  so 
treated,  because  some  may  not  be  susceptible.  The  inoculating  fluid 
is  generally  a  bouillon  culture  of  the  germs,  twenty-four  hours  old, 
and  the  amount  used  is  from  one  to  ten  cubic  centimeters.  Some- 
times the  inoculation  is  made  with  the  filtrate  of  a  bouillon  culture, 
from  which  all  living  germs  are  held  back  by  filtering  through  por- 
celain. After  making  these  tests  the  analysis  for  the  ptomaines 
and  toxins  are  conducted  as  follows : 

Only  absolutely  pure  chemicals  can  successfully  be  employed 
in  this  work  and  this  must  be  ascertained  beforehand  by  evaporat- 
ing the  ether  used  and  analyzing  the  residue  for  poisonous  bodies. 

The  Stas-Otto  Method.    (Vaughan  and  Novy.)  . 

This  method  depends  upon  the  following  facts  :  ( i )  The  salts 
of  the  alkaloids  are  soluble  in  water  and  alcohol  and  generally  in- 
soluble in  ether,  and  (2)  the  free  alkaloids  are  soluble  in  ether  and 


206  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

are  removed  from  alkaline  fluids  by  agitation  with  ether.  These 
principles  are  capable  of  great  variations  in  their  application.  The 
usual  directions  are  as  follows :  Treat  the  mass  under  examination 
with  about  twice  its  weight  of  90  per  cent  alcohol,  and  from  ten 
to  thirty  grains. of  tartaric  or  oxalic  acid;  digest  the  whole  for  some 
time  at  about  I58°F.  and  filter.  Evaporate  the  filtrate  at  a  tem- 
perature not  exceeding  95°  F.,  either  in  a  strong  current  of  air  or 
in  vacuo  over  sulphuric  acid.  Take  up  the  residue  with  absolute 
alcohol,  filter,  and  again  evaporate  at  a  low  temperature.  Dissolve 
this  residue  in  water,  render  alkaline  with  sodium  carbonate,  and 
agitate  with  ether.  After  separation  remove  ether  wnth  a  pipette,  or 
by  means  of  a  separator,  and  allow  it  to  evaporate  spontaneously. 
The  residue  may  be  further  purified  by  redissolving  in  water  and 
again  extracting  with  ether.  Chloroform,  amylic  alcohol  and  ben- 
zene are  used  as  solvents  after  extraction  wnth  ether. 

Brieger's  Method. — The  substance  under  examination  is  di- 
vided as  fine  as  possible,  and  then  heated  with  w^ater  slightly  acidi- 
fied with  hydrochloric  acid.  During  the  heating  care  must  be  taken 
that  the  feebly  acid  reaction  is  maintained  and  the  heat  should  con- 
tinue for  only  a  few  minutes.  The  liquid  is  then  filtered  and  con- 
centrated, at  first  on  a  plate,  and  then  on  the  w^ater-bath,  to  a  syrup. 
An  extraction  of  the  syrup  is  made  with  96  per  cent,  alcohol  and 
the  filtered  extract  is  treated  with  a  warm  alcoholic  solution  of  lead 
acetate.  The  lead  precipitate  is  removed  by  filtration,  the  filtrate 
evaporated  to  a  syrup  and  again  extracted  with  96  per  cent  alcohol. 
The  alcohol  is  driven  off;  the  residue  taken  up  with  water;  traces 
of  lead  removed  with  hydrogen  sulphid;  and  the  filtrate  acidified 
with  hydrochloric  acid,  evaporated  to  a  syrup,  which  is  extracted 
with  alcohol,  and  the  filtrate  precipitated  with  an  alcoholic  solution 
of  mercuric  chlorid.  The  mercury  precipitate  is  boiled  with  water, 
and  on  account  of  the  differences  in  solubility  of  the  double  com- 
pounds with  mercury,  one  ptomaine  may  be  separated  from  others 
at  this  stage  of  the  process. 

The  mercury  filtrate  is  freed  from  mercury,  evaporated,  and 
the  excess  of  hydrochloric  acid  carefully  neutralized  with  soda  (the 
reaction  is  kept  feebly  acid)  ;  then  it  is  again  taken  up  with  alcohol 
to  free  it  from  inorganic  salts.  The  alcohol  is  evaporated,  the  resi- 
due taken  up  with  water,  the  remaining  traces  of  hydrochloric  acid 
neutralized  with  soda,  the  whole  acidified  with  nitric  acid  and  treated 
with  phosphomolybdic  acid.  The  phosphomolybdate  double  com- 
pound is  separated  by  filtration  and  decomposed  with  neutral  ace- 
tate of  lead.  This  is  hastened  by  heating  on  the  water  bath.  The 
lead  is  removed  by  hydrogen  sulphid,  the  filtrate  is  evaporated  to  a 
syrup  and  taken  up  with  alcohol,  from  which  many  ptomaines  are 
deposited  as  chlorids,  or  double  salts  may  be  formed  in  the  alcoholic 
solution. 


DECOMPOSITION  CAUSED  BY  MICRO-ORGANISMS.  207 

The  chlorids  deposited  from  the  alcohoHc  solution  are  seldom 
pure  and  may  be  isolated  by  precipitation  with  gold  chlorid,  plat- 
inum chlorid,  or  picric  acid,  and  on  account  of  the  differences  in 
solubility  of  these  salts,  the  purification  is  rendered  more  easy. 
The  chlorid  of  the  base  is  obtained  by  removing  the  metal  with 
hydrogen  sulphid,  while  the  picrate  is  taken  up  with  water,  acidified 
with  hydrochloric  acid,  and  repeatedly  extracted  with  ether,  in  order 
to  remove  the  picric  acid. 

These  remarkable  methods  are  not  the  only  ones  used  in  ex- 
tracting bacterial  poisons,  but  they  are  sufficiently  complicated  to 
test  the  skill  of  even  first-class  chemists  and  may  be  used  as  a  means 
of  defense  against  falsely  reported  discoveries  of  ptomaines  in  food 
products. 

We  will  conclude  this  subject  by  naming  some  of  the  poisonous 
ptomaines  which  have  been  isolated  by  some  of  the  most  eminent 
chemists  in  the  world.  (Tetanotoxin  CgH^N)  —  (Amylanim  C5 
H13N) — Hexylamin  CgHigN) — Trimethylenediamm  CgHgNg) — 
(Susotoxin  CioHsgNo). —  (Methvl  guanidin  C2H7N3) — (Asellin 
C25H32N4)— (Neurin  QH^.^NO),— (Cholin  C5Hi5NOo)o(My- 
datoxin  CgHigNOa)  — (Mytilotoxin  C5H15NO2)— (Gadinin  C7H17 
NO2)— (Typhotoxin  C7Hi,N0o)— (Muscarin  C5H15NO3)— (Te- 
tanin  C13H30N2O4). —  (Tyrotoxicon,  Mydalein,  Spasmotoxin, 
Adiamin,  Peptotoxin  and  many  others  unnamed.) 


208  CANNING  AND  PRESERVING  OP  FOOD  PRODUCTS. 

CHAPTER  VL 

Sterilization 

Nature  of  Spores.  Cleanliness  in  Manufacturing.  Disposition  of 
Waste  Material.  The  Venting  Process.  Vacuum  Machinery. 
Discontinuous  Sterilization.  Preservatives  Formed  in  Sterili- 
zation. 


vSTERITJZATlON. 

Its  Application  in  Canning  and  Preserving 

To  sterilize  any  material  is  to  make  it  barren,  or  to  destroy  the 
bacteria  present,  or  render  them  incapable  of  reproduction.  In 
its  broad  meaning,  it  might  embrace  the  use  of  any  chemical  or  phys- 
ical force,  capable  of  destroying  reproductive  pow^ers,  but  in  its  re- 

\stricted  sense  it  means  to  apply  heat  to  destroy  micro-organisms 
or  to  hinder  their  vegetating  power. 

,  The  large  number  of  bacteria  which  do  not  produce  spores 

are  easily  destroyed  at  temperatures  ranging  from  140  to  180  de- 
grees F.,  moist  heat,  and  to  this  class  belong  nearly  all  pathogenic, 
lactic  and  acetic  bacteria,  and  also  yeast  and  molds,  although  these 
are  more  resistant  to  heat  than  the  bacteria  mentioned.  To  the 
other  class  which  produce  spores  belong  the  butyric,  subtilis  and 
mesenteric  families,  and  a  few  to  the  Pathogenic.  There  are  a 
great  number  of  species  belonging  to  these  families,  some  of  which 
produce  spores  of  great  vitality,  and  these  spores  are  able  to  resist 

Jboiling  for  hours,  owing  to  a  thick  membrane  which  protects  the  vi- 

(tal  power  within.  They  resemble  dry  beans,  peas,  corn,  etc.,  and 
the  older  they  are,  the  closer  do  their  heat-resisting  membranes 
enclose  their  life.  I  have  seen  beans  so  hard  after  several  years 
drying,  that  they  refused  to  absorb  water  for  two  weeks  and  then 
very  slowly,  so  when  spores  become  old  it  is  reasonable  to  suppose 
that  they  shrink,  and  the  pores  of  their  membranes  become  im- 
pervious to  moisture,  so  that  they  require  very  high  temperature 
to  deprive  them  of  vitality.  So  small  do  these  spores  become,  that 
even  the  microscope  fails  often  to  reveal  their  presence  in  fluids, 
and  one  writer  has  conceived  the  idea  that  they  might  not  become 
wet,  if  air  containing  them  should  be  forced  through  sulphuric  acid. 
This  might  seem  ridiculous  on  first  thought,  but  when  we  consider 
their  minuteness  and  the  repellant  force  of  certain  substances 
against  moisture,  it  does  not  seem  so  unreasonable.     If  we  fill  a 


STERILIZATION.  209 

glass  graduate  with  water,  sO'  that  the  surface  is  not  disturbed, 
there  will  be  a  distinct  difference  between  the  height  of  the  water 
at  the  center  from  that  at  the  edge  of  the  glass;  the  glass  holds  the 
rising  fluid  down  below  the  service  level,  unless  it  be  first  moist- 
ened. A  thin  cover-glass  will  float  on  a  fluid,  although  its  specific 
gravity  is  much  greater;  the  repellant  force  will  bank  up  the  fluid 
all  around  it,  so  that  it  will  float  below  the  surrounding  surface  of 
the  fluid,  which  has  no  power  to  wet  the  upper  surface  of  the  glass. 
The  same  phenomenon  may  be  observed  if  a  small  needle  be  gently 
laid  on  the  surface  of  the  fluid.  To  my  mind  it  seems  reasonable 
to  suppose  that  some  spores  are  so  constructed  that  they  will  repel 
the  surrounding  fluid  and  do  not  become  wet  until  certain  changes 
are  produced  in  that  fluid,  either  by  increased  temperature  or 
nutritive  power,  or  by  chemicals  which  may  attack  the  cell  mem- 
brane. 

For  general  sterilizing  purposes,  the  packers  of  hermetically' 
sealed  goods  use  moist  heat.  This  kind  of  heat  is  far  better  than 
dry  heat,  because  of  the  character  of  the  cell  membrane  of  bacteria 
and  spores.  It  is  by  the  absoi*ption  of  moisture  that  bacteria  are 
able  to  grow  and  vegetate,  and  their  spores  are  enabled  to  send 
forth  young  rods.  Steam  heat  therefore  exerts  a  violent  action 
against  life  and  destroys  it  much  quicker  than  the  same  tempera- 
ture of  dry  heat.  The  action  of  the  cell  membrane  against  dry  heat 
might  be  likened  to  that  of  asbestos.  For  sterilizing  canned  goods, 
the  packers  use  several  devices  which  are  all  good,  but  the  thermal 
death  point  of  the  bacteria  present  in  the  cans  is  a  problem. 

There  are  a  number  of  bacteria  closely  resembling  one  another, 
which  produce  spores  greatly  varying  in  heat-resisting  power;  the 
most  resistant  si>ecies  known  was  discovered  by  Globig,  which  is 
found  on  potatoes,  and  is  called  the  "Potato  bacillus."  This  or- 
ganism produces  spores  able  to  li\'e  through  six  to  ten  hours 
or  more  of  boiling  temperature.  Almost  all  the  bacteria  having 
great  heat-resisting  power  are  found  in  cultivated  soil,  and  are 
present  on  the  stems,  leaves  and  edible  portions  of  all  vegetables. 
If  the  juices  of  these  plants  become  infested  with  spores  of  these 
various  species,  the  problem  of  sterilization  is  a  deep  one ;  too  much 
heat  destroys  the  flavor  of  the  canned  product,  and  as  a  rule  cannot 
be  fixed  broad  enough  to  take  in  the  thermal  death  point  of  all  heat- 
resisting  germs,  since  nearly  all  vSpeices  are  able  to  grow  on  most 
of  the  vegetables  used  for  canning,  excepting  tomatoes ;  for  instance, 
the  juice  of  peas  nlay  be  used  to  cultivate  in  pure  culture  the  "Potato 
bacillus,"  and  we  all  know  that  a  process  sufficientlv  high  to  destroy 
the  spores  of  this  microbe  would  cook  the  peas  to  pieces  and  destroy 
the  flavor.  When  decomposition  of  vegetables  sets  in,  especially  while 
yet  in, the  field,  or  when  they  are  piled  up  with  the  pods,  leaves  or 


210  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

vines  still  present  among  them,  the  way  is  made  easy  for  the  devel- 
opment of  numerous  spore-bearing  bacteria,  which  find  a  suitable 
nutritive  material  in  the  exposed  juices,  to  multiply  and  produce 
spores.  When  cultures  are  made  of  the  bacteria  found  on  the  stems, 
leaves,  pods  or  husks,  the  varieties  of  spore-bearing  bacteria  found 
are  numerous.  As  we  have  stated  before,  the  most  hardy  bacteria 
are  found  in  the  soil,  and  they  are  growing  rapidly  on  all  dead 
matter  which  nature  carries  down  to  them ;  their  spores  are  formed 
and  under  the  warm  summer  sunshine  they  become  dry  and  light, 
and  are  carried  by  currents  of  air  to  all  parts  of  the  field,  finding  lodg- 
ment on  the  growing  plants,  they  lie  dormant  until  they  gain  entrance 
to  nutrient  juices,  when  they  begin  a  new  life  cycle  and  form  the 
same  hardy  spores  which  are  often  found  in  cans  of  spoiled  goods. 

Now,  to  make  the  point  clear,  if  packers  use  raw  material  which 
is  bruised  or  partially  decomposed,  they  have  much  to  contend  with, 
because  they  must  process  this  material  long  enough  to  destroy  all 
manner  of  bacteria,  which  gain  entrance  to  the  deep  portions. 

The  value  of  a  blanching  bath  for  peas,  string  beans,  asparagus, 
etc.,  is  twofold;  it  arrests  decomposition  and  it  washes  away  many 
resistant  forms  of  germs,  but  if  the  deepest  tissues  and  fibres  are 
penetrated,  the  washing  does  not  carry  away  the  destroying  agents. 

There  are  some  points  worthy  of  consideration  here,  and  we 
refer  to  the  nature  of  certain  vegetables,  and  their  nutritive  value 
for  various  bacteria.  Every  kind  of  fruit  and  vegetable^has  a  chem- 
ical composition  peculiar  to  itself;  some  are  strongly  acid,  while 
others  are  nearly  neutral,  some  have  considerable  starch  and  al- 
bumen, while  others  are  rich  in  sugar  or  carbohydrates ;  some  have 
antiseptic  compounds,  such  as  benzoic  acid,  phenol,  salicylic  acid, 
creosote,  formaldehyde,  etc.,  but  the  amount  is  only  small,  yet  suffi- 
cient to  prevent  the  growth  of  many  species  of  bacteria.  There 
are  certain  species  of  bacteria  which  are  always  found  associated 
with  a  given  kind  of  vegetable  or  fruit,  which  furnish  the  germs 
with  all  their  vital  requirement;  other  species  may  be  present,  but 
are  checked  in  their  growth  by  the  greater  multiplication  of  the  reg- 
ular species.  Certain  bacteria  pecuHar  to  peas  may  be  able  to  force 
entrance  to  the  juices,  while  others  would  find  nutrition  only  on  ex- 
posed surfaces.  This  accounts  for  prevalence  of  certain  species 
on  a  particular  kind  of  vegetable. 

The  processor  becomes  familiar  with  a  certain  temperature, 
prolonged  for  a  given  time,  which  seems  to  sterilize  the  same  veg- 
etables, fruits,  etc.,  year  after  year,  without  very  much  spoilage, 
but  suddenly  the  old  rule  fails  and  whole  batches  of  canned  goods 
spoil  because  of  a  new  species  of  bacteria  having  taken  the  field; 
the  old  process  is  not  sufficient  to  destroy  the  spores  of  the  new 
variety.  How  necessary  it  is  to  know  the  reason  for  this !  Only 
a  knowledge  of  bacteria  can  help  him. 


STERILIZATION. 


211 


\ 


Plate  68.     Globig's  Potato  Bacillus,  Flagellated 

Photomicrograph  of  Globig's  Potato  bacillus,  showing  numerous  flagella.     Magnified  1,200  diameters. 


*  %•  *^  •S 

Plate  69.     Globig's  Potato  Bacillus 

Photomicrograph  showiug  Numerous  Spores  which  are  larger  than  the  Rods  in   Diameter.     Culture  from 
Agar,  isolated  from  Spoiled  Corn.     Stained  with  Fuchsin.     Slide  preparation  by  Author.     Magnified  X  1,000. 


STERILIZATION.  213 

There  are  some  natural  causes  for  the  presence  of  new  vari- 
eties of  bacteria  which  suddenly  make  their  appearance  in  canned 
goods.  The  weather  often. has  an  influence  on  the  chemical  com- 
position oTTaw  material;  during  some  seasons  there  may  be  more 
sugar  and  less  starch,  or  there  may  be  less  sugar  and  increased 
acidity,  due  to  rains  or  drought.  We  have  all  noticed  that  it  is 
sometimes  the  very  finest  looking  corn  which  spoils.  We  have  seen 
tomatoes  crack  open  by  sunshine  after  rains,  and  later  have  heard 
the  popping  of  the  corks  from  the  catsup  bottles,  or  seen  the  cans 
swell  in  various  pi les. 

The  nature  of  the  soil  may  ha  re  an  influence.  The  farmers 
have  been  growing  for  us  the  same  products  year  after  year  in 
ground  cared  for  and  manured  regularly ;  suddenly  it  becomes  nec- 
essary to  procure  a  certain  fertilizer  and  a  number  go  in  together 
and  buv  fertilizer  which  changes  the  chemical  composition  of  the 
truck  raised  on  the  ground. 

Now  when  changes  take  place  in  the  chemical  composition  of; 
raw  material,  it  may  not  be  just  suited  to  the  same  varieties  of  bac- 
teria formerly  found  associated  with  it,  but  the  changed  constit- 
uents form  the  nutritive  elements  necessary  for  the  luxuriant  growth 
of  more  formidable  species. 

The  problem  of  sterilization  becomes  a  scientific  study,  when 
such  changes  as  we  have  mentioned  take  place  in  the  composition 
of  Ihe  raw  material.  To  be  sure,  anyone  may  be  able  to  sterilize 
any  kind  of  product  by  giving  it  a  high  temperature  for  a  long  time, 
more  than  is  actually  necessary;  but  to  know  just  how  much  is  suffi- 
cient, and  to  be  sure  that  the  goods  will  keep  well,  is  where  good 
judgment  is  required.  If  the  packers  would  supply  themselves 
with  a  good  microscope,  with  one-twelfth  oil  immersion  ob- 
jective and  an  incubator,  it  would  be  a  very  easy  matter  to 
kngw_  positively  if  a  given  process  was  sufticient.  A  can  or 
a  number  of  cans  from  each  day's  work  could  be  placed  in  the  incu- 
bator, and  if  the  sterilization  was  riot  complete  the  bacteria  would 
develop  at  a  blood  temperature  within  twenty- four  to  forty-eight 
hours;  juice  from  these  cans  could  be  made  into  a  hanging  drop, 
andjf  any  bacteria  happen  to  be  present,  the  microscope  would  re- 
veaLJJiem.  Most  of  the  spore-bearing  bacteria  are  motile,  and 
there  would  be  some  present,  even  in  small  quantities  of  the  juice, 
long  before  the  formation  of  sufficient  gas  to  swell  the  cans.  A 
nlunber  of  tests  could  be  made  with  juice  of  these  cans,  and  the 
packer  could  keep  close  watch  on  the  sterilizing  process,  and  in 
many  cases  could  reduce  the  time,  wdiich  would  insure  a  better 
flavor. 

The  exhaust  process,  or  the  filling  of  cans  with  hot  material, 
prior  to  the  final  process,  is  a  good  plan  for  two  reasons :  The  hot 


214  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

material  is  expanded  by  the  heat,  which  produces  a  vacuum  after 
the  cans  are  sterilized ;  the  heat  thus  given  the  material  will  shorten 
the  final  process.  The  temperature  given  in  the  final  process  varies 
according  to  the  material  and  size  of  the  cans.  A  thermal  death 
point  for  the  bacteria  present  is  first  determined,  then,  to  this  must 
be  added  the  time  required  for  that  heat  to  reach  th%  center  of  the 
cans;  for  this  purpose  the  manufacturers  of  thermometers  have 
made  a  device,  with  a  self-registering  thermometer  to  indicate  the 
temperature  at  the  center  of  the  can;  by  repeated  experiments  the 
time  required  for  penetration  may  be  known.  The  mercury  tube 
has  a  constriction  which  prevents  the  return  of  the  metal  to  the 
bulb,  and  when  it  is  removed  will  show  the  exact  maximum  heat 
at  the  center  of  the  can.  These-little  devices  are  inexpensive  and 
should  _be  Jised  by  every  .packer. 

We  have  referred  to  the  vacuum  produced  by  the  exhaust  pro- 
cess, or  filling  of  cans  with  hot  material  prior  to  the  final  or  steril- 
izing process;  the  vacuum  is  convenient  for  drawing  the  tin  back 
to  normal  shape  after  it  has  been  swelled  at  both  ends  in  the  ster- 
ilization. There  was  a  strong  belief  among  packers  that  a  vac- 
uum was  absolutely  necessary  for  preserving  canned  goods,  and 
there  still  exists  a  belief  of  this  kind,  not  only  among  some  packers, 
but  machinery  men  as  well.  Tlie  vacuum  has  no  value  as  a  means 
of  preventing  decomposition  by  bacteria.  Even  if  a  very  power- 
ful vacuum  could  be  produced,  it  would  not  prevent  the  hardy  spore- 
Bearing  bacteria  from  developing  in  cans  under-processed.  Even 
if  the  oxygen  remaining  in  the  partial  vacuum  could  be  replaced  by 
hydrogen  or  carbonic  acid  gas,  these  bacteria  would  still  be  able  to 
igrow  and  multiply.  Nearly  all  of  the  species  identified  with  spoil- 
age of  canned  goods  grow  well  in  the  presence  or  absence  of  oxy- 
:gen,  and  though  aerobes,  generally  are  also  facultative  anaerobes. 

The  temperature  and  time  required  for  sterih'zation.  depends 
upon  the  nature  of  the  bacteria  present,  and  the  character  of  the 
material.  Different  fruits  anja  vegetables  vary  in  their  chemical 
composition.  There  are  also  (narked  differences  in  the  same  vege- 
tables and  fruits  grown  in  dift'erent  parts  of  the  world.  Tomatoes 
grown  in  the  Northern  States,  Michigan,  Wisconsin  and  Minne- 
sota, have  less  acid  and  more  sugar  than  those  grown  in  Iowa,  In- 
diana, New  Jersey,  and  Delaware.  The  different  varieties  of  fruits 
and  vegetables  vary  in  their  composition,  so  that  the  conditions  are 
different  in  one  locality  from  those  in  another.  Even  in  the  same 
locality  two  kinds  of  peas  or  corn,  etc.,  may  require  dift'erent  steril- 
izing processes,  owing  to  the  presence  on  one  of  a  particularly 
hardy  spore  bearing  baccillus,  which  may  not  be  g-rowing  on  the 
other  variety. 


STERILIZATION.  215 

It  is  not  possible,  therefore,  to  make  a  bacteriological  investiga- 
tion of  spoilage  in  one  locality  and  make  the  conclusions  fit  the 
conditions  in  all  cases.  One  or  two  bacteriologists  have  made  care- 
ful study  of  sour  corn,  and  isolated  a  number  of  bacteria  found  in 
the  cans,  but  these  bacteria  are  not  always  in  sour  com;  some  of 
them  may  be  found,  and  even  other  species  entirely  different  in  an- 
other location.  The  same  thing  applies  to  peas,  beans,  asparagus, 
tomatoes  and  all  kinds  of  fruits,  but  these  fruits  do  not  vary  so 
much  in  all  their  germ  flora  as  do  vegetables. 

The  difference  of  time  and  temperature  required  for  sterili zing- 
different  kinds  of  vegetables  has  been  a  perplexing  problem  for 
canners.  It  is  not  generally  understood  why  peas  should  keep 
at  a  temperature  below  that  of  corn  fully  twenty  minutes  less  in 
time,  or  why  peaches  should  keep  when  processed  several  minutes 
less  than  tomatoes. 

The  difference  is  due  to  two  facts — there  are  different  species 
of  micro-organisms  and  there  are  chemical  differences  in  composi- 
tion which  render  the  juice  of  one  antiseptic  to  germs  found  in  the 
juice  of  another.  As  a  rule  bacteria  do'  not  grow  in  juices  w-hich 
have  a  marked  acid  reaction,  although  there  are  notable  exceptions 
folhis,  but  generally  speaking  the  more  acid  the  juice  contains,  the 
fewer  the  species  of  bacteria.  The  hardy  spore  bearing  bacteria, 
as  a  rule,  do  not  thrive  well- on  acid  media,  even  small  quantities 
being  detrimental  to  their  growth.  The  slight  addition  of  sugar 
however,  overcomes  the  antiseptic  properties  of  some  juices,  and 
the  spore-bearing  bacilli  are  able  to  grow  to  some  extent.  The 
writer  has  often  been  surprised  on  opening  cans  of  under  processed 
goods,  which  were  bulged  at  both  ends  from  the  enormous  pressure 
of  gases  within,  to  find  how  few  bacteria  the  juices  actually  con- 
tained. The  spores  had  developed  and  some  reproduction  had  re- 
sulted, until  the  amount  of  acid  formed  had  acted  as  an  antiseptic, 
andjiiultiplication  had  apparently  ceased. 

It  often  happens  that  the  can  springs  a  leak  from  the  pressure, 
and  the  gas  is  liberated,  then  the  bacteria  from  the  air  gain  entrance 
and  the  acids  are  attacked  and  reduced  to  fatty  or  volatile  acids,  the 
original  agents  having  gone  into  a  resting  state,  or  formed  spores. 

The  climatic  conditions  of  certain  localities  have  something  to 
do  with  the  varieties  of  bacteria  found  associated  with  spoilage.  In 
some  of  the  Central  and  Southern  States  there  are  much  hardier 
varieties  prevalent  than  in  Northern  vStates,  or  the  New  England 
States,  consequently  a  process  that  is  giving  satisfaction  in  Maine 
may  not  be  sufficient  for  sterilizing  the  same  product  in  Ohio. 

Cleanliness,  and  proper  disposition  of  zmste  niaterial,  are  prom- 
inent factors^  in  sterilization.  There  are  times  during  the  canning 
season  when  the  raw  products,  or  material  only  partially  cooked. 


216  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

are  exposed  to  the  ravages  of  bacteria  floating-  on  dust,  and  matter 
held  in  suspension  by  the  atmosphere.     This  is  the  case  when  break- 
downs occur  in  the  machinery,  or  wdien  the  work  is  not  carried  on 
systematically,  or  when  the  receipts  of  raw  material  are  greater  than 
the  canning    capacity.     The^  danger    is    greatest    where    partially 
cooked  material  is  exposed  to  the  air.     The  spore  bearing  bacteria 
and  the  putritive  anaerobes  are  liable  to  set  up  iinperceived  decompo- 
sition, and  elaborate  foul  substances  such  as  indol  and  skatol,  or 
may    produce    bitterness    or    disagreeable    acidity.     The    partially 
cooked  material  offers  a  more  suitable  nutrition  for  these  true  sca- 
vengers, because  che  ceilulose  or  fibre  is  softened  and  the  juices  are 
richer  in  albuminous  compounds,  which  furnish  them  with  all  their 
vital  requirements.     The  danger  from  these  bacteria  is  not  so  great 
where  absolute  cleanliness  is  exercised  and  proper  disposition  is 
made  of  waste  material.     If  the  waste  material  such  as  cobs,  hulls, 
husks,  vines,  stems,  peelings,  seeds  and  trimmings,  are  dumped  in 
heaps  in  the  vicinity,  the  air  will  be  found  teeming  with  the  spores 
of  these  micro-organisms,  ever  ready  to  fall  into  nutrient  material, 
and  there  begin  their  work  assigned  by  nature,  the  tearing  down 
process  of  fermentation  or  putrefaction.     If  accumulations  are  al- 
lowed to  stand  from  one  year  to  another,  the  spores  of  thesejba^- 
TenaTmay  become  so  dry  and  hard  that  the  old  and  tried  sterilizing 
process  will  fail  to  be  effective.     There  is  great  truth  in  these  state- 
iments,  viz.,  that  age  will  toughen  the  spore  membrane  and  that  the 
I  spore  protoplasm  will  dry  and  shrink  and  be  more  impervious  to  the 
jaction  of  heat,  and  require  longer  time  to  absorb  moisture  so  nec- 
lessary  for  rapid  sterilization.     Thus  the  ordinary  sterilizing  pro- 
cess becomes  ineffective.     The  same  danger  may  lurk  in  the  dirt  and 
dust  of  the  factory;  if  the  floors  and  machines  are  not  kept  clean, 
by  the  liberal  use  of  soap,  hot  water  and  steam,  the  harmful  bacteria 
will  be  present  in  all  parts  of  the  building,  in  such  numbers  as  to 
produce  chemical  changes  where  least  suspected.     The  e^-il  of  un- 
cleanliness  is  not  confined  to  the  breeding  of  bacteria  alone,  but  flies, 
insects,  rats,  mice,  etc.,  are  drawn  by  the  opportunities  of  getting 
food,  and  the  whole  factory  will  soon  be  in  a  very  bad  condition. 

How  is  it  possible  to  produce  fine  goods  where  the  entire  es- 
tablishment gives  the  impression  of  careless,  neglectful  methods! 
Unclean  methods  breed  carelessness  in  employees,  and  this  becomes 
evident  in  the  character  and  quality  of  the  goods  turned  out.  The 
sterilization  is  accomplished  only  at  a  time  and  temperature  beyond 
that  actually  required  in  a  clean,  well-regulated  factor}',  and  the 
product  has  lost  the  color  and  flavor  which  we  might  suppose  once 
existed. 

When  Isaac  Winslow  began  to  pack  corn  in  tin  cans,  he  used 
onlv  an  open  batli  process  at  first.  .   He  boiled  the  cans  for  several 


STERILIZATION.  217 

hours  and  succeeded,  strange  to  say,  in  keeping  a  large  per  cent,  of 
his  goods.  Our  readers  are  famiHar  with  the  history  of  his  after 
faikires,  and  his  final  adoption  of  the  steam  retort.  That  he  was 
ever  able  to  sterilize  corn  by  simph^  boiling  the  cans  has  been  a 
source  of  wonder  to  the  writer;  certainly  none  of  the  well-known 
heat  resisting  bacteria  were  present,  or  if  so  they  had  not  become  ac- 
customed to  corn.  This  theory  seems  to  have  some  foundation,  be- 
cause bacteria  are  known  to  accommodate  themselves  to  certain  ma- 
terial when  forced  to  grow  in  it;  for  instance,  the  Bacillus  Diph- 
theria grows  very  scantily  upon  ordinary  agar,  when  planted  fresh 
from  the  false  membrane  of  a  diphtheria  patient,  yet  after  trans- 
planting upon  the  same  medium  a  number  of  times,  it  grows  quite 
well  and  if  kept  in  a  cool  place,  loses  its  virulence  to  a  certain  extent. 
The  Typhoid  Bacillus  becomes  less  virulent  after  repeated  trans- 
planting, and  the  same  characteristic  has  been  demonstrated  in 
various  species.  So  it  may  be  when  corn  was  first  grown  in  this 
country  that  the  hardy  spore  bearing  bacteria  did  not  at  first  find 
suitable  nourishment,  except  in  some  cases.  Now  it  is  fair  to  pre- 
sume that  when  once  started  the  bacilli  became  accustomed  to  corn, 
and  their  nature  having  changed  through  that  nourishment  their 
spores  more  easily  attacked  the  corn  in  following  years.  The  open 
bath  process  suddenly  failed  and  Winslow  and  his  contemporaries 
lost  almost  their  entire  pack. 

It  is  well  remembered  that  corn  was  sterilized  a  few  years 
ago  hy  3.  certaia  process  which  is  not  now  effective  in  all  cases,  so  we 
cannot  but  hold  to  the  theory  that  the  most  hardy  species  of  bacteria 
are  gradually  becoming  accustomed  to  corn,  and  perhaps  other  vege- 
tables. No  one  can  say  that  new  species  are  being  created,  but 
such  may  be  the  case;  if  so,  then  we  may  be  able  to  explain  the 
necessitated  increase  of  temperature  for  sterilization.  There  are, 
however  (found  on  vegetables),  so  many  species  closely  resembling 
each  other,  differing  only  in  one  or  two  characteristics,  that  we  are 
strengthened  in  our  first  theory,  and  we  may  ascribe  those  differ- 
ences to  the  changes  in  the  materials  upon  wh'.ch  they  have  habit- 
uated themselves. 

By  increased  temperature  in  the  sterilizing  process,  certainly 
the  color  and  flavor  suffered  to  some  extent,  the  color  particularly, 
and  the  demand  made  by  the  trade  for  nearly  natural  colors  in 
canned  goods,  forced  evil  practices  upon  the  packers,  corn  was 
bleached  and  peas  were  colored  with  copper,  and  tomatoes  received 
the  ''sunshine"  from  aniline  dyes.  In  some  cases  the  sterilization 
was  reduced,  and  antiseptics  added.  This  helped  to  preserve  the 
color,  but  the  quality  suffered  even  more  than  by  increased  tempera- 
ture. In  the  course  of  time  these  methods  passed  the  limit,  and 
some  of  the  goods  put  upon  the  market  were  unsightly,  and  the 


218 


CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


flavor  was  completely  lost.  Tomatoes  and  catsup  were  colored 
beautiful  carmines,  and  looked  more  like  red  paints  than  articles  of 
food. 

By  the  excessive  use  of  chemicals  and  colors  to  shorten  the 
sterilization,  the  public  turned  away  from  canned  goods  of  this  na- 
ture, and  it  is  well  remembered  how  the  prices  dropped  to  almost 
nothing  (several  years  ago).  The  people  were  getting  liberal 
doses  of  all  kinds  of  chemicals  and  colors,  in  nearly  every  manu- 


Fig.  31 


factured  food  product  brought  to  the  table,  so  they  clamored  for 
pure  food  laws,  elected  State  Food  Commissioners,  aided  by  skilled 
chemists,  and  the  tide  has  turned  the  other  way.  There  is  no 
doubt  that  these  abuses  will  have  settled  the  lawful  right  to  use  cer- 
tain colors  and  preservatives,,  there  may  be  some  condiments  ex- 
cepted, but  certainly  none  will  be  permitted  in  canned  goods,  nor 
are  they  necessary. 


STERILIZATION.  219 

The  apparatus  for  sterilizing  canned  goods  is  simple,  consist- 
ing of  retorts  with  lids  which  may  be  sealed;  into  these  live  steam 
is  conducted  and  used  either  dry  or  with  water  and  the  retorts  are 
exhausted  to  keep  up  the  circulation,  while  the  temperature  is  main- 
tained by  a  thermometer  and  steam  gauge. 

For  alLvegetables,  meats,  soups  and  foods  of  albuminous  na- 
ture, wjiichfurni__sh  all  the^elements  of  nutrition  for  spore  bearing 
bacteria,  a  temperatu_re  of  250°  F,  is  better  than  any  lower  degree, 
for  the  reason  that  spores  perish  at  that  degree  of  heat  quickly;  the 
time  required  is  variable  owing  to  the  numerous  complications  we 
have  described,  viz.,  the  various  species  of  bacteria  to  be  destroyed, 
the  character  of  the  material,  and  its  heat  penetrability.  Our  ex- 
perience leads  us  to  believe  that  dry  live  steam  is  more  reliable 
than  water,  because  circulation  is  more  thorough,  but  there  is  al- 
ways some  danger  of  discoloration,  which  may  be  avoided  as  fol- 
lows. A  water  connection  is  made  with  the  water  line  by  means  of 
steam  hose,  to  the  lid  of  the  retort,  and  a  large  overflow  is  made  near 
the  top  of  retort,  so  that  a  considerable  volume  of  water  may  be  let 
into  it.  just  as  the  temperature  drops  to  about  220°  F.  after  the 
cans  have  received  a  full  process.  The  sudden  rush  of  cold  water 
chills  the  goods,  and  stops  the  cooking  which  is  still  going  on  within 
the  cans.  Otherwise  when  the  cans  are  thus  cooking,  and^the  lid  is 
opened  suddenly,  the  air  striking  the  cans  will  cause  discoloration, 
but  if  the  retort  is  completely  filled  with  cold  water  (before  opening 
the  lid),  the  color  w^ill  remain  good,  and  there  will  be  no  scorched 
taste  unless  the  sterilization  has  been  unnecessarily  prolonged. 
250°  F.  is  equal  to  about  fifteen  pounds  pressure  and  may  weaken 
the  seams  of  the  cans  unless  the  chilling  is  done  (with  water)  before 
their  exposure  to  the  atmospheric  influences. 

Another  method  of  sterilization  coming  into  favor  is  the  cal- 
cium process,  which  in  some  measure  seems  like  a  return  to  ancient 
methods,  yet  improved  as  it  is,  has  some  advantage  over  the  ordin- 
ary steam  retort  system.  The  principle  of  obtaining  a  higher  de- 
gree of  heat  than  boiling  water  in  a  fluid,  is  based  on  the  specific 
gra^'it^-  ^^  the  fluid.  By  adding  calcium  to  water  the  specific 
gravity  IS  increased  until  temperatures  of  240°  and  even  250°  F. 
may  be  obtained,  without  ebullition,  consequently  there  is  little  or 
no  escaping  steam,  and  the  temperature  may  be  maintained  at  a 
very  small  expense,  when  compared  to  the  cost  of  generating  steam 
for  retorts. 

The  latest  device  consists  of  a  long  tank  filled  to  a  certain  depth 
with  calcium  water,  through  which  the  crates  containing  the  can^ 
are  dragged  on  a  carrier,  which  is  slowly  speeded  to  give  the  re- 
quired time  for  sterilization.  After  the  cans  are  sterilized,  they  are 
carried  through  running  water  to  cleanse  them,  and  this  also  stops 


220  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

the  cooking  which  is  going  on  inside  the  cans  after  they  have  passed 
through  the  calcium  bath.  This  process  has  the  advantages  men- 
tioned above,  being  a  fuel  and  labor-saving  method,  but  it  cannot 
be  used  successfully  for  sterilizing  glass  goods,  which  require  hig;h 
temperatures.  Glass  goods  are  difficult  to  sterilize,  owing  to  the 
breakage  and  the  small  expansive  properties  of  glass.  G[ass  goods 
of  all  kinds  may  be  sterilized  with  dry  steam  at  any  temperature  up 
to  250°  F.,  if  the  precautions  are  taken  to  raise  and  lower  the  tem- 
perature very  slowly.  The  successful  sterilization  of  glass  goods 
depends  largely  upon  the  quality  and  thickness  of  the  glass,  also  the 
method  of  sealing*.  The  French  have  been  importing  all  kinds  of 
fruits  and  vegetables  put  up  in  glass,  but  nearly  all  such  goods  are 
preserved  with  antiseptics  of  one  kind  or  another,  and  while  they 
look  well,  are  not  to  be  compared  to  the  goods  packed  by  many  Am- 
erican canners.  Glass  seems  to  have  the  advantage  over  tin,  in  the 
opinion  of  many  persons,  because  there  is  a  mistaken  and  widespread 
belief  that  there  is  some  danger  of  metallic  poisoning  from  tin 
and  the  solder  and  flux  used  in  sealing.  It  is  a  question,  however, 
if  there  be  more  metal  in  tin  goods  than  in  some  of  the  highly- 
colored  French  glass  goods  sold  on  the  market. 

The  writer  has  made  a  number  of  analyses  of  ^'arious  canned 
goods  for  tin,  lead  and  zinc,  and  the  quantity  of  the  first  two.  are 
almost  incalculably  small.  The  most  definite  amount  of  tin  and 
lead  were  obtained  from  canned  pineapple  and  California  fruits,  but 
no  appreciable  amount  was  obtained  from  these.  Some  samples 
showed  the  presence  of  more  or  less  zinc,  due  to  careless  use  of 
soldering  solution.  The  old  method  of  brushing  the  caps  with  an 
ordinary  paste  brush  dipped  in  zinc  chlorid  has  given  way  to  the 
beautiful  little  machines  which  carry  the  solution  on  pencil  brushes 
around  the  crease  of  each  can,  allowing  none  to  be  sucked  in  through 
the  vent  hole. 

Of  course,  glass  goods,  if  packed  with  care  and  without  the  use 
of  preserving  agents  and  metallic  colors,  are  entirely  free  from 
metals,  excepting  where  they  are  found  in  composition.  Some 
^'egetable3  have  iron  and  copper  in  composition.  Tomatoes  grown 
in  ^Vestern  Pennsylvania  contain  some  copper. 

The  sterilization  of  goods  in  glass  imparts  a  si ightlj  scorched 
taste,  because  it  is  impossible  to,  chill  with  water.  The  cooking 
goes  on  until  the  temperature  drops  below  the  boiling  point. 

Another  method  of  sterilizing  canned  goods  has  found  favor 
among  the  packers  of  canned  meats  and  special  food  products.  The 
apparatus  is  a  monstrous  affair  requiring  a  great  deal  of  room. 
The  cans  are  placed  in  the  carriers  and  allowed  to  pass  through 
oil,  which  is  heated  to  a  certain  temperature.  This  apparatus  is 
used  bv  the  Armour  Packino-  Co.  of  Chicaofo,  and  the  results  are 


STERILIZATION.  221 

very  "satisfactory.  After  the  cans  pass  through  the  oil,  they  are 
drained  and  then  carried  through  an  alkahne  sohition,  and  then 
through  running  water. 

There  are  several  methods  employed  now  to  avoid  the  old 
'Senting"  process  and  even  in  the  canning  of  meats  this  is  entirely 
obviated.  The  object  of  the  venting  process  was  two-fold,  viz.,  to 
heat  tjie  contents  of  the  can  to  obtain  a  vacuum,  and  to  drive  off 
unpleasant  gases.  Outside  of  tomatoes,  there  are  hardly  any  pro- 
ducts cold  packed  unless  special  apparatus  is  employed.  For  or- 
dinary canning  all  that  is  necessary  is  to  heat  the  syrup  or  liquid 
which  is  used  to  cover  the  fruits  and  vegetables,  or  to  heat  the  vege- 
tables before  filling  into  the  cans;  corn  is  thus  heated  before  the 
filling. 

There  are  several  devices  used  to  pack  certain  goods  without 
pre^•ious  heating  or  'Venting" ;  all  these  are  modifications  of-  the 
vacuum  process.  The  cans  are  passed  into  a  machine  which  ex- 
hausts the  air  by  a  vacuum  pump,  and  while  in  vacuo  are  sealed. 
The  machine  used  in  packing  meats  is  interesting,  because  the  "tip- 
ping" or  "dotting"  is  done  in  vacuo.  The  machine  is  round  and 
carries  the  cans  in  15  pounds  vacuum,  under  a  glass  window;  the 
inside  is  illuminated  by  incandescent  light,  and  a  small  round  disc  of 
solder  is  melted  by  a  copper,  which  is  heated  by  electricity.  The 
operator  can  look  down  through  the  window  and  melt  the  solder 
over  each  hole  as  the  cans  pass ;  when  all  have  been  "tipped,"  the 
vacuum  is  released  and  the  cans  pass  out,  when  they  are  inspected 
for  leaks. 

The  old  method  of  venting  canned  meats  was  difficult,  costly 
and  uncleanly.  The  cans  were  filled  cold,  and  a  piece  of  tin  was 
bent  and  soldered  onto  the  under  side  of  each  cap  to  prevent  the 
meat  from  coming  up  into  the  hole,  which  was  made  with  an  awl 
after  the  cans  were  heated  the  first  time.  The  juice  and'  grease 
would  squirt  all  over  everything  when  the  cans  were  punctured  and 
the  closing  of  the  holes  was  quite  difficult,  requiring  skilled  help. 

There  are  several  kinds  of  vacuum  machines  on  the  market,, 
but  they  require  special  cans.  The  lids  of  these  cans  are  prepared 
with  patent  cement.  The  cans  are  put  into  the  vacuum  machine 
with  the  lids  loosely  placed,  and  when  the  air  is  exhausted  the  lids 
are  forced  down  into  place  and  the  cement  holds  the  vacuum  in  the 
cans.  The  cans  are  made  without  soldering,  except  the  body  seam, 
the  sealing  being  completed  by  crimping  the  flanges  of  the  body 
together  with  the  rims  of  both  tops  and  bottoms.  The  cement  com- 
ing between  the  tw^o  edges  prevents  leakage. 

These  machines  are  used  in  European  canneries  and  give  good 
satisfaction.  Recently,  improved  machines  have  been  built  in  Am- 
erica for  making  these  cans.     These  cans  are  also  coated  with  a 


222  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

substance  which  is  not  attacked  by  fruit  acids.  The  inside  coated 
cans  are  preferable  for  goods  of  dehcate  color.  The  ordinary  cans 
are  thus  coated  also. 

There  is  another  method  of  sterilization  used  largely  in  bac- 
teriological work  to  destroy  the  bacteria  in  culture  media,  which 
become  altered  by  high  temperatures.  It  is  called  '^Discontinuous 
Sterilization"  and  was  discovered  by  Prof.  Tyndall  during  his  ex- 
periments and  efforts  to  overthrow  the  theor}^  of  "spontaneous 
generation,"  advanced  by  Von  Liebig  and  his  contemporaries. 

Prof.  Tyndall  experimented  with  all  kinds  of  infusions  made 
from  meats,  vegetables  and  grains,  trying  various  degrees  of  heat 
from  212°  to  300°  F.,  and  prolonging  the  time  for  hours.  These 
experiments  are  recorded  in  Tyndall's  ''Floating  Matter  of  the  Air." 
There  is  no  question  but  that  his  experiments  at  300°  F.  were  faulty 
wherever  he  failed  to  sterilize  his  infusions  in  an  oil  bath.  We  have 
conducted  numerous  experiments,  using  A'arious  temperatures,  and 
up  to  this  time  have  never  discovered  any  species  of  bacteria  whose 
spores  could  withstand  250°  F.  moist  heat  for  more  than  a  few 
minutes.  This  statement  must  not  be  applied  to  the  sterilization  of 
canned  goods,  nor  any  material  which  is  impervious  to  heat:  it  a]j- 
plies  only  to  that  temperature  directly  upon  the  spores,  which  are  in 
solutions  or  materials  easily  penetrated  by  heat. 

Tyndall's  infusions  were  sterilized  in  glass  flasks  having  a  thin 
tube  for  escaping  steam,  wdiich  was  sealed  by  melting  the  glass  to- 
gether while  the  steam  was  escaping.  This  would  not  be  reliable, 
since  the  temperature  must  be  lowered  to  melt  the  glass  together, 
or  else  there  would  be  a  fine  hole  in  the  glass,  which  would  be  an  en- 
trance for  bacteria  from  the  air.  If  the  infusions  were  cooled  to 
allow  the  perfect  sealing  of  the  glass,  a  vacuum  would  form  in  the 
interval  and  spores  from  the  air  could  find  entrance. 

There  is  no  question  but  that  250-  F.  moist  heat  for  twenty 
minutes  will  destroy  all  known  spores,  if  the  necessary  precau- 
tions are  taken  to  avoid  contamination  from  the  air.  It  is  mar- 
velous how  a  small  hole  in  the  soldering  of  a  can  will  be  the  means 
of  spoiling  the  contents.  Holes  which  are  as  small  as  a  needle 
point,  are  wide  open  doors  for  such  infinitely  small  vital  powers  as 
spores,  and  it  is  often  difficult  to  find  some  of  these  leaks  in  spoiled 
cans.  Through  a  hole  the  size  of  a  period  (.)  50,000  spores  could 
pass  side  by  side  into  a  can  w'ithout  touching  the  metal. 

Discontinuous  sterilization  is  conducted  as  follows :  Moist 
heat,  usually  212°  F.,  is  applied  to  the  material  in  water  bath,  for 
a  time  ranging  from  twenty  minutes  to  one  hour,  after  which  it  is 
placed  in  a  cool  place  for  one  day,  and  the  same  process  is  then  ap- 
plied a  second  time,  and  this  is  continued  for  three  days,  so  that 
the  material  receives  four  processes,  which  render  it  sterile. 


STERILIZATION.  223 

The  scientific  principle  is  based  on  the  time  required  for  spores 
to  vegetate.  As  we  have  stated  in  previous  pages,  the  vegetating 
cells  are  easily  destroyed;  very  few,  indeed,  are  able  to  withstand 
1 80°  F.,  and  almost  all  perish  at  165^  F.  Now  the  spores,  being 
very  resistant  to  heat,  are  simply  softened  during  the  first  one  or 
two  processes,  and  readily  perish  when  they  begin  to  vegetate. 
Probably  most  of  them  are  destroyed  in  two  heating,  but  a  few  of 
the  drier  forms  may  require  a  day  or  two  longer  to  swell  up  and 
vegetate,  so  that  the  four  heatings  will  as  a  rule  destroy  all. 

As  we  have  stated,  there  are  certain  materials  which  are  chem- 
ically altered  by  high  temperatures,  and  it  is  necessary  to  resort  to 
the  discontinuous  method  in  order  to  prevent  undesirable  changes. 
Gelatin  loses  its  solidifying  properties  if  heated  to  230°  F.  Milk 
isvery  much  altered  when  heated  even  to  boiling  temperature,  there 
being  formed  such  substances  as  formaldehyde,  dioxygen  and  cal- 
cium citrate,  the  latter  being  thrown  down  as  a  precipitate.  Milk 
is  therefore  sterilized  at  about  165°  F.  for  one  hour,  on  five  consecu- 
tive days,_j:o  avoid  these  alterations. 

There  are  constantly  made  improvements  on  all  methods  of 
work  and  we  believe  that  the  discontintious  sterilization  of  canned 
goods  by  practical  means  offers  a  good  field  for  experiment  and 
study.  On  a  small  scale  in  laboratory  work  it  is  successful.  All 
kinds  of  infusions  of  meats  and  vegetables  are  easily  sterilized  (in 
test  tubes  and  flasks)  by  simply  plugging  the  necks  with  cotton  and 
heating  in  the  manner  just  described.  The  color  and  flavor  of  such 
vegetables  as  corn,  peas,  string  beans,  asparagus,  cauliflower,  lima 
beans,  etc.  (when  sterilized  discontinuously),  are  very  much  su- 
perior to  those  of  the  regular  canned  goods,  which  have  received 
240°  or  250°  F.  The  writer  has  made  a  number  of  such  experi- 
ments and  the  results  are  gratifying-. 

Sterilization  by  electricity,  such  as  a  direct  current  or  an  al- 
ternating current  or  the  X-rays  is  not  reliable,  and  by  the  first  two 
certain  chemical  changes  are  produced  which  are  undesirable.  It 
was  hoped  and  claimed  that  the  X-rays  would  accomplish  steriliza- 
tion by  causing  paralysis  of  the  bacterial  cells,  but  repeated  experi- 
ments have  demonstrated  only  failures. 

Sterilization  by  heat  is  the  oiily  method  of  value  for  the  can- 
ning industry.  There  are  some  special  products  which  are  pre- 
served by  chemicals,  but  these  will  no  doubt  be  regulated  by  pure 
food  laws  in  such  a  manner  that  only  a  minimum  quantity  of  pre- 
servatives will  be  permitted,  or  perhaps  none. 

One  fact  must  not  be  lost  sight  of,  however,  and  that  is  that  1 
various  fruits    and   vegetables   contain    within   themselves    certain 
acids  and  salts  which  make  them  easy  to  sterilize  by  heat;  these  ele- 
ments of  composition  act  as  antiseptics  and  in  some  cases  as  disin- 
fectants for  many  of  the  spore-bearing  species  of  bacteria. 


224  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

It  must  not,  therefore,  be  inferred  that  a  certain  process  by 
heat  .actually  destroys  all  life,  but  that  all  bacteria  are  prevented 
from  multiplying  through  the  destruction  of  some  (by  heat)  and 
the  antiseptic  power  of  the  juices.  This  may  hold  good  so  long  as 
perfect  fruits  and  vegetables  are  used  and  the  complete  elimination 
of  all  foreign  matter  is  observed,  but  should  unsound  material  be 
used  or  adulterations  find  favor,  or  should  dirt  or  foreign  matter 
get  mixed  in  with  good  material  through  carelessness,  the  condi- 
tions will  be  changed,  and  the  regular  heating  may  not  prevent  de- 
composition. By  avoiding  adulterations  and  observing  the  slnctest 
rules  of  cleanliness  losses  will  be  minimized. 

Certain  fruits  contain  antiseptics,  as  we  have  stated,  and  cer- 
tain antiseptic  compounds  are  formed  by  oxidation  of  sugars  and 
fats,  by  the  influence  of  light  and  at  250  degrees  F.  These  antisep- 
tics play  a  very  important  part,  as  we  have  shown  in  sterilization, 
and  it  is  our  purpose  to  study  the  various  compounds  found  in 
canned  goods,  and  also  the  various  antiseptics  which  are  used  to 
accomplish  sterilization  in  special  food  products. 


PRESERVATIVES.  225 

CHAPTER  VII. 

Preservatives 

What  are  Preservatives? — Preservatives  are  not  Ordinarily  Used 
in  Canned  Goods. — Some  Food  Products  Require  Them. — Nat- 
ural Origin  of  Preservatives  in  Food  Products. — Statements 
made  by  Various  Authorities  Analyzed  and  Criticised. — Sterilized 
Catsups,  Preserves  and  Fruit  Butters  not  Satisfactory  to  the 
Trade. — Some  Opposing  Arguments  Answered. 


It  is  well  known  that  certain  chemicals  when  added  to  food 
have  a  restraining  influence  upon  the  bacteria,  yeasts  and  molds 
which  are  associated  with  its  decomposition.  Some  chemicals  pre- 
vent the  multiplication  of  bacteria  and  are  called  antiseptics,  while 
others  will  kill  the  germs  and  also  the  spores  and  are  classed  as 
disinfectants.  It  is  difficult,  however,  to  draw  the  line  between 
antiseptics  and  disinfectants,  for  the  reason  that  large  quantities  of 
the  chemicals  known  as  antiseptics,  may  also  prove  to  be  germicidal 
and  therefore  disinfectants,  and,  on  the  other  hand,  small  quantities 
of  chemicals  known  to  be  germicidal,  may  not  destroy  the  life  of 
bacteria  and  therefore  only  antiseptic.  Some  antiseptics  when 
used  in  limited  quantities  favor  the  growth  of  certain  bacteria  and 
are  used  in  obtaining  pure  cultures ;  the  chemical  will  prevent  the 
growth  of  some  varieties  Avhich  ordinarily  overrun  the  culture  plates. 
The  term  antiseptic  is  applied  to  a  number  of  chemicals  which  are 
used  to  some  extent  in  the  preparation  of  foodstuffs,  principally 
catsups,  sauces,  preserves,  etc.  They  have  been  found  in  canned 
goods  in  some  cases,  no  doubt,  purposely  added  by  the  packers  to 
shorten  their  sterilizing  process,  but  more  commonly  due  to  natiu'al 
causes. 

The  harmful  nature  of  the  various  chemicals  has  been  argued 
pro  and  con  by  the  best  exponents  of  science,  but  their  effect  upon 
the  human  body  is  disputed,  and  the  actual  effect  of  some  is  not 
known.  They  may  be  harmful  or  they  may  not  be.  but  they  are  con- 
sidered (by  the  authorities)  as  unnecessary,  and  "the  burden  of 
proof,  therefore,  rests  upon  those  who  employ  them."  If  they  are 
not  harmful,  then  they  may  be  classed  as  adulterants  (if  used  in 
canned  goods)  from  the  fact  that  they  are  largely  unnecessary  and 
do  not  add  any  nutritive  value  to  the  food.  If  they  are  harmful, 
there  is  sufficient  ground  for  prohibiting  their  use.  There  can  be 
no  possible  argument  for  the  employment  of  chemicals  as  antiseptics 
in  canned  goods; 


226  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

I  do  not  find  that  they  are  used  to  any  great  extent  in  canned 
goods,  the  methods  of  former  years  having  been  superseded  by  the 
more  reHable  and  less  expensive  steriHzation  by  heat  only.  There 
may  be  some  packers  who  use  chemicals  for  preserving  canned 
goods,  but  they  are  very  ignorant  of  their  business.  The  best 
houses  sterilize  all  canned  goods  by  steam  heat  either  directly  or  in- 
directly, and  do  not  increase  the  cost  by  adding  expensive  antisep- 
tics. 

Some  of  the  published  reports  of  antiseptics  found  in  various 
brands  of  canned  goods  are  absurd  and  misleading.  There  have 
appeared  reports  indicating  that  as  many  as  three  different  chemi- 
cals were  found  in  a  single  can.  On  the  face  of  it,  it  is  most  unlikely, 
because  no  packer  would  be  so  foolish  as  to  waste  his  money  in  this 
manner,  and  even  if  he  should  use  the  chemical  method  he  would 
hardly  use  more  than  one  as  an  antiseptic. 

Antiseptics  have  been  too  freely  used  in  some  kinds  of  food  in 
the  past  and  adulterants  have  been  added  to  so  many  varieties  of 
food  that  the  public  has  rebelled  and  food  commissioners  have  been 
employed  to  fix  the  responsibility  upon  guilty  manufacturers  and 
laws  have  been  passed  to  prevent  such  products  from  being  exposed 
for  sale.  Some  of  the  reports  made  by  analytical  chemists  will 
show  to  what  extent  this  has  been  practiced,  and  while  they  may  be 
overdrawn  in  cases,  yet  there  is  no  doubt  that  such  practices  have 
gone  beyond  the  limit  of  tolerance. 

It  was  claimed  by  one  very  radical  food  commissioner  that  it 
was  no  uncommon  occurrence  for  a  person  to  sit  down  .to  a  meal 
having  the  following  list  of  chemicals  included  in  his  diet :  "Ham 
containing  saltpeter ;  canned  corn  containing  saccharin,  salicylic  acid 
and  hyposulphite  of  soda ;  canned  peas  containing  copper  and  alum ; 
tomato  catsup  containing  benzoate  of  sodium  and  coal  tar  dye; 
wheat  cakes  containing  ammonia  or  alum ;  maple  syrup  made  from 
cane  sugar  syrup  and  glucose;  mustard  containing  tumeric;  milk 
containing  formaldehyde;  coffee  artificially  prepared  from  various 
substances;  pepper  containing  ground  cocoanut  shell,  and  butter 
containing  borax.  Verily  one  would  have  an  internal  drug  house 
if  this  were  continued  day  after  day."  It  is  hardly  likely  that  a 
person  w^ould  be  so  unfortunate  as  to  meet  with  all  these  compounds 
in  a  single  meal,  yet  it  might  happen  that  he  would  be  confronted  by 
a  few  of  them  at  least.  The  claim  is  made  that  such  combinations 
must  in  time  cause  trouble  in  the  human  stomach,  because  the  juices 
which  enter  into  the  digestive  processes  were  never  intended  to  per- 
form the  work  of  an  analytical  chemist  three  times  each  day.  If 
such  conditions  actually  existed  there  would  be  some  ground  for 
complaint,  but  canned  goods  packers  are  not  responsible  for  these 
adulterations.     There  are    some    points    worthy    of    consideration 


PRESERVATIVES.  227 

when  dealing-  with  the  question  as  to  whether  antiseptics  shall  be 
prohibited  in  all  food  products.     It  is  well  known  that  bacteria  are 
scavengers  and  more  readily  attack  food  which  has  been  cooked, 
than  food  in  the  raw  state ;  the  cooking  seems  to  soften  those  foods  t 
containing  fibre  and  releases  the  nutrient  juices  and  fluids  upon  \ 
which  the  bacteria  find  suitable    elements    for    growth.     Bacteria  , 
which  produce  ptomaines  and  toxins  and  disease  parasites  also  flour- 
ish upon  cooked  food,  and  if  that  food  is  not  consumed  as  soon  as 
it  is  exposed,  it  may  prove  more  dangerous  than  if  it  contained  an 
antiseptic.     There  are  many  food   products   which   are   not   eaten 
alone,  but  are  used  to  give  flavor  and  relish  to  other  articles  of  pre- 
pared food.     Such  products  may  not  be  entirely  consumed  at  a  sin- 
gle meal  and  may  be  regarded  as  luxuries.     Now,  if  any  of  this 
class  is  subject  to' decomposition  it  would  seem  wise  to  use  a  certain 
per  cent  of  antiseptic  to  preserve  it.     Under  this  head  might  be  I 
mentioned  such  articles  of  food  as  butter,  cheese,  tomato  catsup,  ! 
Chili-sauce,  apple-butter,  peach-butter,  and  other  sauces  and  relishes.  \ 
The  argument  has  been  advanced  that  such  foods  may  be  prepared 
in  small  size  packages,  and  thus  avoid  the  necessity  of  carrying 
over  from  one  meal  to  another,  but  the  expense  would  be  heavy,  and 
in  many  cases  would  not  be  practical,  especially  for  hotels  and  res- 
taurants.    This  is  a  question  worthy  of  careful  consideration  and 
we  believe  that  the  manufacturer  has  a  shade  the  better  of  the  areu- 
ment. 

The  great  mass  of  our  people  do  not  care  to  waste  money  on 
glass  or  tin  packages  of  small  size.  They  want  as  much  as  possible 
of  the  contents,  and  as  little  as  possible  of  the  package  in  their  in- 
vestments, and  we  believe  that  if  a  strict  ruling  were  made  against 
the  employment  of  preservatives,  it  might  prove  to  be  a  burden  on 
the  people  or  else  would  bar  the  masses  from  using  these  luxuries. 
It  is  difficult  to  draw  the  line,  however,  and  a  thorough  test  should 
be  made  of  all  modern  preservatives  to  determine  positively  their 
effect  upon  human  beings  in  the  quantities  ordinarily  employed  in 
food  products.  The  honest  manufacturer  is  ready  to  comply  with 
any  good  national  pure  food  law,  so  long  as  he  is  protected  by  that 
law. 

There  are  some  facts  concerning  antiseptics  which  are  quite 
necessary  to  be  known,  and  it  was  the  author's  privilege  to  bring 
them  out  at  the  convention  of  state  food  commissioners  and  chem- 
ists at  St.  Paul,  Minn.,  in  July,  1903.  Various  antiseptics  are 
formed  naturally  in  fruits  and  vegetable.  Various  antiseptics  are 
formed  during  the  processes  of  manufacture,  especially  where  fer- 
mentation is  employed,  and  where  sterilization  is  accomplished  at 
high  temperatures.  Antiseptics  are  formed  where  certain  food  pro- 
ducts are  exposed  to  stroii^ii|\l^^h^'^^ 

-^  /^     OF  THE    "^A 

i  UNIVERSITY  J 


228  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

Prior  to  this  convention  there  appeared  pubhshed  reports  of 
analyses  made  by -different  state  chemists  who  claimed  to  have  found 
various  antiseptics  in  canned  goods.  Knowing  that  certain  brands 
of  goods  had  been  packed  absolutely  without  the  employment  of 
these  antiseptics,  we  began  a  series  of  analyses  to  determine  their 
origin.  We  found  that  the  chemists'  reports  were  true  in  only  a 
few  cases,  but  we  also  found  that  antiseptics  were  formed  in  the 
manner  stated  above.  The  chemists  who  had  been  conducting  the 
analyses  for  the  people  were  pleased  to  learn  the  results  of  our  in- 
vestigations, which  placed  the  canner  in  a  far  better  light  than  ever 
before.  We  believe  that  much  good  was  accomplished  at  the  con- 
vention and  that  the  chemists  and  manufacturers  understand  each 
other  better;  both  sides  were  fair  and  willingl}'  heard  the  arguments 
pro  and  con. 

There  are  various  fruits  and  vegetables  which  contain  certain 
antiseptics.  Whortleberries  contain  0.6  to  0.8  gram  of  benzoic 
acid  per  liter  (Lafar's  Technical  Mycology,  Section  80) .  ;  raspber- 
ries contain  salicylic  acid  or  phenol,  as  also  does  horseradish,  which 
will  prevent  the  acetification  of  cider  in  one  part  to  three  hundred 
and  fifty.  Currants  contain  benzoic  acid  and  salicylic  acid.  Cher- 
ries, plums,  crabapples,  grapes,  strawberries,  apricots  and  peaches, 
contain  salicylic  acid  in  appreciable  quantities.  An  analysis  of 
cranberries  was  made  by  the  author  to  determine  the  quantity  of 
benzoic  acid  present  naturally  in  them.  From  125  grams  of  cran- 
berries we  obtained  60  milligrams  of  the  preservative.  This  is 
equivalent  to  one  part  to  2c8o,  and  we  are  quite  sure  that  there  was 
still  more  which  could  not  be  extracted.  This  is  a  very  large 
amount  of  preservative  to  be  found  naturally  in  one  of  our  finest 
fruits.  In  Ohio  or  Pennsylvania  any  one  who  sells  cranberries  is 
liable  to  be  arrested  and  fined  for  selling  an  article  of  food  contain- 
ing a  substance  which  is  poisonous  or  injurious  to  health,  according 
to  the  rulings  of  the  pure  food  commissioners,  and  the  decisions  of 
the  courts.  Some  of  the  jams,  preserves,  fruit  butters  and  jellies 
do  not  have  any  more  of  this  preservative  than  occurs  naturally  in 
cranberries.  Why  are  cranberries  so  valuable  and  so  much  relished 
with  turkey  dinners  ?  Is  it  not  because  the  benzoic  acid  assists  di- 
gestion, and  also  prevents  any  decomposition  of  the  food  which  the 
stomach  cannot  quickly  take  care  of?  The  benzoic  acid  prevents 
the  bacteria  from  multiph^ing  until  the  stomach  catches  up  with  the 
unusual  amount  of  work  forced  upon  it. 

Anal3^ses  were  made  of  two  lots  of  green  gages  to  determine 
the  presence  of  benzoic  acid.  These  two  lots  were  obtained  from 
different  places,  which  makes  us  reasonably  sure  that  no  benzoic  acid 
had  been  added  artificially.  500  grams  were  used,  or  about  one 
pound  for  each  extraction,  and  the  seeds  were  broken.  After  pre- 
paring the  fruit  for  the  chloroform,  several  c.  c.  of  25  per  cent  sul- 


PRESERVATIVES.  229 

phuric  acid  was  added,  although  this  is  not  necessary.  The  fruit 
was  then  placed  in  a  separatory  funnel  and  125  c.  c.  of  chloroform 
was  added  and  it  was  shaken  up  well  several  times.  After  a  time 
the  chloroform  was  drawn  off  before  the  formation  of  an  emulsion. 
The  extract  was  divided  into  three  parts  and  after  spontaneous 
evaporation  tested  for  benzoic  acid  with  the  Ferric  chlorid  test,  and 
benzoic  acid  was  found.  Mohler's  test  was  then  used,  converting 
the  benzoic  acid  into  metadiamidobenzoic  acid,  which  confirmed  the 
first  test.  Both  samples  of  green  gages  gave  the  reaction.  Salicy- 
lic acid  has  been  fouad  in  many  different  fruits  as  shown  by  the 

REPORT  I^ROM  MONTANA  EXPERIMI:nT  STATION. 

'^\mong  the  fruits  from  which  we  have  obtained  the  salicylic 
acid  reaction  are  the  following:  Strawberries,  raspberries  (both 
red  and  black),  blackberries,  currants,  plums,  black  cherries,  apri- 
cots, peaches,  Concord  grapes,  crabapples,  standard  apples  and 
oranges.  In  a  few  instances  we  have  this  work  quantitative  with 
the  following  results : 

Currants,  0.57  mg.  acid  per  kilo  of  fruit. 
Cherries,  0.40  mg.  acid  per  kilo  of  fruit. 
Plums,  0.28  mg.  acid  per  kilo  of  fruit. 
Crabapples,  0.24  mg.  acid  per  kilo  of  fruit. 
Grapes,  0.32  mg.  acid  per  kilo  of  fruit. 

These  values,  however,  are  not  absolute,  but  only  comparative, 
and  represent  the  amount  which  we  succeeded  in  extracting  in  each 
case.  We  distilled  the  fruit  with  phosphoric  acid,  extracted  the  dis- 
tillate with  ether,  took  up  with  small  amount  of  water,  and  applied 
the  ferric  chloride  test  after  the  ether  had  evaporated.  Check  analy- 
ses made  with  known  amounts  of  salicylic  acid  showed  that  nearly 
all  of  the  acid  was  extracted  by  this  method.  We  have  also  found 
the  salicylic  acid  reaction  to  be  given  by  tomatoes,  cauliflower  and 
string  beans. 

It  seems  to  us  that  the  bearing  of  this  w^ork  is  very  important, 
particularly  as  regards  the  investigations  of  food  chemists.  While 
these  very  small  quantities  may  not  react  to  the  test  for  salicylic 
acid  as  usually  applied,  especially  in  view  of  the  small  amount  of 
material  generally  worked  upon  (25  grams),  yet  a  knowledge  of 
its  wide  distribution  may  save  reporting,  on  occasions,  materials  as 
adulterated  to  which  salicylic  acid  has  not  been  added.  Knowing 
that  salicylic  acid  may  occur  in  many  of  the  substances,  either  a 
quantitative  determination  will  be  necessary  in  each  case,  or  it  will 
be  well  to  report  only  on  strong  reactions. 

We  were  led  to  this  investigation  by   the   protest   of    a   wxll 
known  reputable  firm,  in  whose  currant  jelly  we  reported  salicylic 


230  CANNING  AND  PRESERVING   OF  FOOD  PRODUCTS. 

acid,  but  which  was  present  in  no  greater  quantity  than  we  have 
since  found  in  fresh  currants.  A  similar  experience  was  lately  had 
in  one  of  the  state  laboratories  for  food  control. 

In  addition  to  the  above  work  we  are  studying  the  distribution 
of  benzoic  acid  in  fruits  and  vegetables,  and  hope  to  be  able  to  pub- 
lish our  results  within  the  year." 

Signed, 

F.  W.  Traphagen, 
Edmund  Burke." 
Journal  American  Chemical  Society. 
March,  1903. 

Tomatoes  and  acid  fruits  contain  antiseptic  properties  in  their 
juices.  Formaldehyde  is  present  in  minute  quantities  in  almost  all 
foodstuff,  which  is  exposed  to  the  action  of  micro-organisms  even 
for  a  short  time,  and  the  official  sulphuric  acid  test  will  show  it 
often  I  have  seen  milk  drawn  from  the  cow's  udder  and  tested  for 
formaldehyde,  which  gave  a  positive  chemical  reaction.  There  are  a 
number  of  raw  materials  which  undergo  partial  fermentation  before 
they  are  worked  into  finished  food  products.  During  that  fermenta- 
tion there  are  formed  various  chemicals  which  are  elaborated  by  bac- 
teria: such  as  phenol,  formic  acid,  sulphites  and  nitrates,  and  enough 
of  these  substances  may  be  present  in  the  finished  goods  to  give 
the  reaction  in  the  official  tests.  Among  the  products  which  under- 
go fermentation  as  a  part  of  the  manufacturer's  process  are  pickles, 

i  olives,  onions,  sauerkraut,  tomatoes  for  catsup,  cauliflower,  herbs. 

'  garlic,  soaked  goods  such  as  navy  beans :  pickled  meats  and  various 
other  raw  materials. 

There  are  formed  in  some  canned  goods  during  sterilization  at 
250°  F.,  such  compounds  as  formic  acid,  formaldeh3^de  and  dioxy- 
gen,  which  are  due  to  the  oxidation  of  fats  and  sugars.  Some  of 
these  are  formed  always  in  canned  corn,  principally  formaldehyde. 
In  the  presence  of  sunlight  also  certain  raw  materials  and  even  fin- 
ished goods  will  form  chemicals  having  strong  antiseptic  proper- 
ties, dioxygen  being  the  most  common  (Novy's  Laboratory  Bac- 
teriology, page  70).  Milk,  when  heated  only  to  212°  F.,  will  show 
;the  presence  of  formic  acid  and  formaldehyde,  and  at  250°  F.  these 
give  a  very  marked  reaction,  and  the  milk  undergoes  chemcial 
changes,  such  as  the  precipitation  of  calcium  citrate  and  the  forma- 
tion of  dark  fission  compounds  having  an  empyreumatic  flavor. 
(Attested  by  numerous  authorities.) 

Xow  we  must  not  understand  by  all  these  statements  that 
enough  of  these  antiseptic  compounds  are  formed  to  arrest  decom- 
position ;  indeed,  such  is  the  case  only  with  a  very  few,  and  even  in 
those,  decomposition  will  eventually  take  place,  but  these  facts  are 


PRESERVATIVES.  231 

brought  out  to  show  that  there  may  be  some  ground  for  the  chem- 
ists' report  on  certain  goods  when  they  state  that  these  antiseptics 
are  present.  On  the  other  hand,  these  facts  will  serve  the  chem- 
ists and  should  enable  them  to  make  allowances  for  products  formed 
during  the  process  of  manufacture,  or  those  which  have  a  natural 
origin  in  raw  material,  used  in  making  up  the  finished  food  product. 
By  conducting  control  tests  and  making  a  careful  study  of  raw  ma- 
terial, the  chemist  will  be  in  a  position  to  state  positively  if  antisep- 
tics are  purposely  added,  or  wliether  they  are  of  natural  origin. 

From  the  very  fact  that  nature  produces  so  many  examples  of 
the  natural  formation  of  compounds  with  marked  antiseptic  prop- 
erties, it  would  seem  that  the  manufacturer  might  be  allowed  to 
follow  nature's  example  in  some  cases. 

So  much  has  been  written  and  said  on  the  harmfulness  of  pre- 
servatives in  food  within  the  last  ten  years  that  any  further  discus- 
sion might  seem  unwarranted.  However,  the  subject  is  one  of 
such  vital  importance  to  manufacturers  of  certain  Food  Products 
and  Table  Condiments,  that  any  information  of  importance  cannot 
fail  to  be  interesting.  A  few  years  ago  the  warfare  waged  against 
the  employment  of  salicylic  acid  became  so  strong,  that  laws  were 
rapidly  passed  to  stop  its  use  in  every  article  intended  for  food  and 
drink.  After  the  passage  of  these  laws,  the  writer  was  one  who 
strongly  urged  the  manufacturers  to  cease  using  the  chemical.  At 
that  time  the  question  was  one  of  obedience  to  State  authority,  how- 
ever dictatorial  it  might  seem.  In  the  absence  of  means  and  data 
to  refute  the  charges  made  by  famous  medical  and  scientific  author- 
ities, the  manufacturers  saw  the  measures  presented  and  passed 
against  them  without  being  al^le  to  oppose  them.  I  have  always 
stood  for  strict  obedience  to  the  laws  governing  the  employment  of 
preservatives  in  Canned  Goods,  and  so  far  as  possible  in  other  food 
products,  but  we  need  a  thorough  test  of  the  statements  made  by 
the  authorities  who  were  responsible  for  the  measures  set  against 
preservatives. 

Personally,  /  believe  that  salicylic  acid  one  part  in  one  thoii' 
sand  is  not  only  non-injurions  zvhen  employed  in  foods  and  drinks, 
"cvhich  are  necessarily  exposed  to  the  action  of  bacterid,  but  is  posi- 
tively beneficial,  having  a  tendency  to  ward  oif  intestinal  diseases,. 
such  as  typhoid  fever  and  cholera. 

I  do  not  wish  to  be  misunderstood  in  this  discussion  of  preser- 
vatives. So  long  as  the  laws  prohibit  the  sale  of  or  exposing  for 
sale  of  goods  preserved  by  means  of  salicylic  acid,  let  us  as  manu- 
facturers, by  all  means  live  in  obedience  to  them,  and  if  we  desire 
a  change  in  the  statutes,  let  us  go  about  it  in  a  way  that  will  over- 
throw the  statements  made  by  those  authorities  who  are  responsible 
for  the  enactment  of  such  laws.     Our  first  step  therefore  will  be  to 


232  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

analyze  the  statement  of  these  authorities  and  present  facts  which 
shall  overthrow  any  theories,  and  if  not  entirely  successful,  to  at 
least  throw  some  shadows  of  doubt  on  them,  it  is  an  old  saying 
that  a  statement  never  loses  anything  by  repetition ;  on  the  contrary, 
it  gathers  force  and  volume  as  it  is  repeated,  so  that  a  simple  doubt- 
ful statement  is  sometimes  expanded  by  frequent  misquotation  into 
an  apparently  positive  fact.  In  the  world  of  science  we  hnd  that 
much  of  the  literature  is  merely  a  copy  of  a  true  investigator's  work, 
and  we  are  mystified  frequently  by  statements  directly  opposite  com- 
ing from  supposed  authorities.  Much  of  the  scientific  literature 
of  the  time  should  probably  never  have  seen  the  light  of  day,  be- 
cause the  statements  made  are  sometimes  not  borne  out  by  facts. 
We  find  this  state  of  affairs  existing  in  the  field  of  science,  where 
a  writer  presumes  to  quote  some  other  writer  as  an  authority.  Prob- 
ably the  preceding  writer  misquoted  an  investigator,  and  a  positive 
error  is  put  down  in  a  text-book  under  the  authorship  of  one,  whose 
titles  protect  him  from  vulgar  criticism,  when  the  fact  is  he  was  per- 
haps too  preoccupied  to  make  the  investigation  for  himself. 

Dr.  J.  Dixon  Mann  is  one  of  the  most  bitter  opponents  of  sali- 
cylic acid  in  food  and  drink,  and  his  evidence  was  accepted  by  the 
British  Parliamentary  Inquiry  Commission,  and  is  a  sample  of  much 
similar  evidence  also  accepted.  I  make  the  quotation  in  full  so  that 
no  mistake  may  be  made  in  the  discussion :  "Last  year  in  the  sum- 
mer, at  lunch  in  the  club,  I  took  to  drinking. cider  and  continued 
taking  it  for  many  weeks.  I  began  to  feel  a  peculiar  tendency  to 
looseness  in  the  bowels;  furthermore,  I  felt  never,  as  it  were, 
thoroughly  relieved  after  motions.  This  went  on  for  a  time  and  I 
could  not  understand  how  it  w^as.  I  thought  it  was  accidental  in 
the  first  place,  but  it  kept  going  on  w^eek  after  Aveek.  I  did  not 
care  to  take  any  medicine  and  I  began  to  cast  about  for  what  possi- 
bly could  be  the  cause  of  it.  I  Avent  over  the  things  I  had  been 
in  the  habit  of  taking,  and  the  things  I  was  taking  at  the  time.  I 
could  not  think  of  anything  until  it  struck  me  about  this  cider;  so 
I  got  a  bottle  of  the  same  sort  from  the  steward  of  the  club,  took 
it  to  my  laboratory,  and  found  salicylic  acid  in  it,  and,  needless  to 
say,  I  have  not  taken  cider  since."  I  want  to  call  particular  atten- 
tion to  the  last  few  clauses  of  this  testimony :  ''And  found  salicy- 
lic acid,'"'  etc.  Why  did  he  not  look  for  malic  acid,  succinic  acid  or 
]some  other  substance?  No,  he  found  salicylic  acid  and  jumped  to 
ithe  conclusion  that  it  was  the  cause  of  his  particular  complaint.  If 
he  had  shown  a  true  scientific  spirit,  is  it  not  reasonable  to  suppose 
that  he  would  have  made  a  quantative  analysis  of  the  salicylic  acid 
contained  in  the  usual  amount  of  cider  which  he  was  in  the  habit 
of  drinking"  each  day?  After  a  time,  when  he  was  in  perfect  health, 
he  could  have  taken  the  same  amount  of  the  acid  mixed  with  other 
food,  and  then  obtained  more  direct  evidence. 


PRESERVATIVES.  233 

It  is  a  source  of  wonder  to  nie  that  such  an  eminent  body  of 
men  as  composed  the  Parhamentary  Inquiry  Commission  should 
accept  such  evidence. 

The  demand  for  preservatives  to  prevent  fermentative  and  put- 
refactive processes  in  certain  kinds  of  perishable  food  is  so  great, 
and  the  interests  involved  are  so  enormous,  that  snap  judgment 
should  not  be  taken  against  them. 

I  have  always  written  against  the  unnecessary  employment  of 
preservatives  in  canned  goods  or  other  foods  which  may  be  steril- 
ized by  heat  only,  for  the  reason  that  it  is  expensive,  unnecessary, 
and  it  is  not  wise  to  overdo  the  thing.  It  would  not  be  wise  to  pre- 
serve everything  with  salt,  it  would  not  agree  with  us  to  have  too 
much  of  it — harmless  and  necessary  as  it  is,  but  we  are  quite  satis- 
fied to  have  our  hams,  sausage,  pickles,  etc.,  so  preserved.  It  would), 
not  be  wise  for  us  to  preserve  all  our  food  with  sugar,  it  would  soon 
make  us  all  sick,  but  we  are  satisfied  to  preserve  our  fruits,  jellies, 
jams,  etc.,  with  it,  because  at  times  we  relish  the  change  of  diet.  ; 
It  would  not  be  wise  for  us  to  preserve  all  our  food  by  smoke  (which 
is  an  application  of  creosote,  phenol,  etc.)  .,  but  we  are  satisfied  to 
have  some  of  our  meat  put  up  in  this  fashion.  It  would  not  be  v\ase 
to  preserve  all  our  food  by  sterilization  in  hermetically  sealed  pack- 
ages, because  we  want  a  change,  yet  we  are  satisfied  to  have  a  great 
variety  so  put  up  for  winter  use.  Therefore  an  indiscriminate  use ' 
of  salicylic  acid  would  be  unwise,  but  when  restricted  to  such  foods 
as  are  subject  to  chemical  changes  by  bacteria,  it  would  be  the  part 
of  wisdom  to  permit  its  use,  provided  it  is  not  injurious  to  health. 

It  has  been  so  declared  by  a  number  of  authorities  on  the  fol-  ■ 
lowing  grounds : 

1.  "It  is  an  antiseptic  and  anti-fermentative,  and  is  therefore 
liable  to  interfere  with  the  digestive  processes  by  destroying  the 
digestive  ferments." 

2.  "After  absorption  it  is  apt  to  injure  the  general  health,  and 
to  interfere  with  nutrition." 

3.  "It  is  an  irritant,  and  is  therefore  apt  to  injure  the  mucous 
membrane  of  the  stomach  and  intestinal  canal." 

In  the  report  of  the  Department  Committee  appointed  to  in- 
quire  into  the  Use  of  Preservatives,  etc.,  presented  to  both  Houses 
by  command  of  His  Majesty,  London.  1901  (page  96),  is  the  testi- 
mony of  Dr.  Robert  Bell,  Fellow  of  the  Faculty  of  Physicians  and 
Surgeons  of  Glasgow,  and  Fellow  of  the  Royal  College  of  Surgeons 
of  Edinburg.  He  stated  that  he  and  his  family  had  knowingly  and 
regularly  taken  food  containing  antiseptics  for  eighteen  years  and 
without  a  sign  of  harm  to  any  of  them.  "During  the  whole  of  that 
period  we  have  never  had  a  single  case  of  illness  in  the  house;  when 
scarlet   fever,   measles,   whooping-cough   and  other  ailments  were 


2U      CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

rampant,  there  was  not  a  single  one  of  our  children  ill.  There  is 
another  family  that  I  know  very  much  in  the  same  position  as  our- 
selves." 

In  papers  read  before  the  Liverpool  Medical  Institution  on 
November  20,  1902,  by  Dr.  C.  J.  MacAlister,  of  Edinburgh,  and 
Dr.  T.  R.  Bradshaw,  of  Dublin,  they  gave  their  experiments  with 
salicylic  acid  on  digestive  processes,  and  the  digestive  ferments. 
Quoting  their  report  fully  they  said :  *'In  this  inquiry  we  have  no- 
thing to  do  with  the  organized  living  ferments  (bacteria,  yeasts, 
molds,  etc.)  .  ;  these  are  certainly  killed  by  salicylic  acid,  and  its 
efficacy  as  a  food  preservative  depends  upon  that  very  fact ;  but  we 
have  found  that  the  digestive  processes  will  proceed  in  the  presence 
of  the  acid  even  in  a  solution  of  i  to  500,  which  is  practically  satur- 
ated. 

Our  first  experiment  was  made  with  pepsin  which,  if  active, 
should  dissolve  2,500  times  its  weight  of  hard-boiled  egg,  and  the 
Pharmacopoea  provides  the  following  test  for  its  activity:  "If  12.5 
grams  of  coagulated  and  firm  white  of  egg,  125  c.  c.  of  acidulated 
water  containing  0.2  per  cent  muriatic  acid,  0.005  gramme  of  pepsin 
be  digested  together  at  105°  Fahr.  for  six  hours  and  shaken  fre- 
quently, the  coagulated  white  of  egg  should  dissolve,  leaving  some 
flakes  in  solution.  Having  ascertained  the  activity  of  a  specimen 
of  pepsin  by  this  experiment,  we  repeated  it  in  two  flasks  each  con- 
taining the  above  specified  ingredients  in  their  proper  proportions, 
but  to  one  of  the  flasks  0.250  gram  of  pure  salicylic  acid  (which 
had  previously  been  dissolved  in  eight  c.  c.  of  boiling  water)  w^as 
added,  and  at  the  end  of  six  hours  it  was  found  that  in  the  flask  con- 
taining salicylic  acid,  there  was  only  a  small  amount  of  white  of 
egg  left,  none  being  left  in  the  other  flask."  They  go  on  to  say, 
however,  that  the  addition  of  salt  to  a  tube  containing  pepsin  and 
white  of  egg  gave  practically  the  same  results,  then  they  sum  up 
the  results  of  their  experiments  in  words  as  follows :  ''We  have 
found  that  salicylic  acid  exerts  about  the  same  retarding  influence 
on  the  digestive  processes,  as  do  many  articles,  such  as  kitchen  salt, 
which  are  always  present  in  a  mixed  diet.  .  .  .  the  question  therefore 
is  not  whether  salicylic  acid  delays  digestion  at  all,  but  whether  it 
does  so  to  a  greater  extent  than  other  bodies,  such  as  kitchen  salt, 
which  form  part  of  an  ordinary  diet."  * 

The  experiments  of  these  two  eminent  authorities  bring  out  the 
fact  that  salicylic  acid  does  not  interfere  with  natural  digestion,  and 
makes  a  clear  distinction  between  organized  or  living  ferments,  such 
as  bacteria,  yeasts  and  molds,  and  the  unorganized  ferments  or  di- 
gestive enzymes,  pepsin  being  most  prominent.  The  opponents  of 
salicylic  acid  have  never  shown  the  proper  spirit  of  investigation. 


PRESERVATIVES.  235 

but  rather  a  kind  of  theoretic  deduction,  jumping  from  one  hypothe- 
sis to  a  conclusion  without  the  sohition  somewhat  after  this  style. 

HYPOTHESIS — Salicylic  acid  destroys  bacteria  which  are 
ferments. 

CONCLUSION — Therefore  digestive  processes  are  impeded 
because  they  depend  upon  ferments. 

We  can  readily  see,  therefore,  how  false  the  conclusion  must 
be  if  it  is  made  to  depend  upon  the  hypothesis,  where  the  bacteria 
are  called  ferments  without  differentiation  from  unorganized  fer- 
ments such  as  pepsin.  We  know  that  the  living  ferments  are  de- 
stroyed by  the  change  produced  in  the  cell  protoplasm,  resulting  in 
plasmolysis,  but  in  the  unorganized  ferment  there  is  no  cell  proto- 
plasm and  the  action  of  the  preservative  cannot  therefore  be  the 
same. 

'  It  should  also  be  borne  in  mind  that  the  opponents  of  salicylic 
acid  have  generally  taken  abnormally  strong  solutions  of  salicylic 
acid,  to  maintain  their  claims.  Xo  person  ever  takes  this  acid  at 
meal  time  as  strong  as  a  cold  water  solution,  yet  this  is  a  favorite 
(amount  employed  in  experiments,)  by  those  who  would  convince 
the  people  that  they  are  dying  of  slow  poisoning. 

An  official  of  the  Department  of  Agriculture  recently  stated 
that  ''The  burden  of  proof,  that  preservatives  are  harmless  to  man, 
rests  with  the  manufacturers  who  use  them.''  Such  a  statement, 
when  closely  analyzed,  is  a  deduction  drawn  from  the  testimony  of 
various  medical  authorities  which  have  declared  that  preservatives 
are  poisons  and  injurious  to  man.  It  implies  that  since  preserva- 
tives have  been  so  declared  by  those  who  ought  to  know,  direct  evi- 
dence to  the  contrary  must  be  produced  by  manufacturers  who  use 
them.  Therefore,  some  of  them  stand  condemned  as  harmful,  be- 
cause many  authorities  have  stated  that  in  their  opinion  such  was  the 
case. 

The  task  of  proving  the  fallacy  of  many  statements  advanced 
by  the  opposition  is  no  easy  one.  The  public  mind  is  already  to 
some  extent  prejudiced  against  preservatives  in  food,  simply  be- 
cause some  authorities  have  made  the  assertion  that  they  w^ere  harm- 
ful. There  are  a  number  of  condiments  which  are  commonly  pre- 
served with  such  chemicals  as  salicylic  acid,  benzoate  of  sodium, 
and  borax,  the  last  two  particularly.  The  condiments  so  preserved 
may  be  sterilized  by  heat  only  and  they  will  remain  pure  and  unfer- 
mented  as  long  as  the  container  is  hermetically  sealed.  As  a  rule 
these  condiments  have  a  very  delicate  flavor  which  is  greatly  injured 
by  a  sterilizing  process  sufficiently  prolonged  to  destroy  the  yeasts, 
molds  and  spores  of  bacteria  present  in  them.  I  have  been  con- 
ducting a  series  of  experiments  with  such  goods  for  the  past  six 
years.     Many  carloads  of  condiments  put  up  in  glass  and  sterilized 


236  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

by  heat  only  have  been  sent  out  to  the  trade.  It  is  a  remarkable 
fact  that  such  goods  have  failed  to  give  general  satisfaction  for 
three  reasons.  They  have  a  slightly  scorched  taste.,  or  a  pasteurized 
taste  and  odor.  The  natural  color  is  somewhat  darkened  and  the 
goods  soon  spoil  after  the  containers  are  opened.  We  have  found 
that  tomato  catsup  which  has  been  sterilized  by  heat  only  is  greatly 
injured  in  flavor  and  will  not  keep  for  more  than  five  days  after  the 
bottles  are  opened.  Frequently  fermentation  sets  in  about  the  third 
or  fourth  day  and  mold  will  be  visible  to  the  eye  in  four  or  five  days. 
Another  remarkable  fact  brought  out  in  these  experiments  was 
the  preference  shown  by  the  consumers  for  condiments  prepared 
with  preservatives  over  the  same  goods  sterilized  by  heat  only.  In 
many  cases  the  facts  were  made  clear  to  the  consumer.  The  conse- 
quence was  that  much  of  the  pure  goods  still  remains  unsold  on 
the  grocer's  shelves,  while  those  prepared  with  preservatives  are 
selling  rapidly. 

Catsup  both  with  and  without  preservatives,  has  been  placed 
throughout  Kentucky,  Minnesota  and  the  Dakotas,  and  a  large 
per  cent  of  that  sterilized  b}^  heat  only  remains  unsold,  and  the  trade 
has  been  greatly  injured  owing  to  the  loss  of  flavor. 

Now  let  us  examine  the  reasons  for  this  difference  in  flavor. 
Why  is  it  that  the  flavor  is  injured  more  by  heat  than  by  preserva- 
tives. It  is  w^ell  known  that  preservatives  destroy  flavor,  especially 
if  used  in  excess,  and  we  know  that  heat  will  not  injure  the  flavor 
very  much  unless  it  is  prolonged. 

In  preparing  table  condiments  with  preservatives,  the  manu- 
facturer does  not  plan  to  destroy  the  organized  ferments  such  as 
molds,  yeasts  and  bacteria,  but  to  prevent  their  multiplication  or 
growth.  The  chemical  changes  caused  by  fermentation  are  pro- 
duced during  the  multiplication  of  the  organized  ferments.  The 
elements  necessary  for  the  multiplication  of  ferments  are  obtained 
from  the  carbohydrates  and  other  complex  substances,  and  there  are 
formed  new  chemical  compounds  greatly  di fleering  in  taste  and  odor 
from  the  original  substance.  Therefore  preservatives  are  added  in 
just  suflicient  amounts  to  prevent  the  multiplication  of  these  fer- 
ments. No  attempt  is  made  to  destroy  them,  because,  as  a  rule, 
they  are  non-pathogenic  and  are  not  harmful  to  the  human  organ- 
ism in  small  numbers.  Very  few  of  the  preservatives  ordinarily 
used  in  preserves,  apple-butter,  tomato  catsup.  Chili-sauce,  etc.,  are 
antiseptic,  strictly  speaking,  and  certainly  they  are  not  germicidal 
in  the  quantities  used.  This  accounts  for  the  spoilage  of  such  con- 
diments after  a  time,  because  ordinary  preservatives  finally  lose 
their  preventative  power. 

Sterilization  by  heat  only  is  a  far  different  problem.  All  spores 
of  yeasts,  molds  and  bacteria  must  be  destroyed  absolutely.     One 


PRESERVATIVES.  237 

or  two  spores  are  just  as  dangerous  as  millions,  if  they  remain  alive. 
From  one  spore  there  will  spring  into  existence  many  millions  of 
the  same  species  within  a  very  short  time,  where  the  temperature 
and  other  conditions  are  favorable.  In  order  to  completely  sterilize 
table  condiments  considerable  heat  is  necessary,  owing  to  the  density 
of  the  goods  and  the  size  of  the  container.  Goods  of  this  kind  are 
usually  sold  in  glass,  because  tin  is  not  suitable  for  them,  owing  to 
their  high  acidity  which  attacks  the  tin  plate  vigorously.  Steriliza- 
tion requires  boiling  for  perhaps  thirty  or  forty  minutes  to  destroy 
all  spores.  The  organisms  near  the  outside,  of  course,  perish 
quickly,  but  those  in  the  center  do  not  get  the  required  temperature 
for  a  considerable  time,  varying  with  the  diameter  of  the  container 
and  the  density  or  penetrability  of  the  goods.  Certain  portions  of 
such  packages,  therefore,  recei\'e  more  heat  than  is  necessary  for 
the  destruction  of  ferments,  and  of  course,  the  flavor  suffers  ac- 
cordingly. If  such  goods  could  be  heated  uniformly,  the  loss  of 
flavor  would  still  be  greater  than  in  the  same  goods  containing  pre- 
servatives sufficient  to  inhibit  bacterial  growth,  because  complete 
destruction  is  necessary  in  the  one,  while  inhibition  only  is  necessary 
in  the  other. 

Our  claim  for  the  necessity  of  preservatives  in  food  of  slow 
consumption  is  a  good  one,  because  it  has  been  demonstrated  that 
the  people  prefer  such  goods  with  as  near  the  natural  flavor  as  it 
is  possible  to  make  them,  and  sterilization  by  heat  does  destroy  much 
of  the  original  flavor.     Our  conclusions  are  thus  summed  up : 

1.  The  ordinary  preservatives  employed  for  preserving  goods 
of  slow  consumption  are  valuable  and  necessary,  because  in  no 
other  way  can  the  original  flavor  of  such  goods  be  retained. 

2.  The  consumer  prefers  this  class  of  goods  even  when  he 
knows  that  preservatives  ha\'e  been  used  to  keep  them  in  an  unfer- 
mented  state. 

This  does  not  dispose  of  the  question,  "Are  such  preservatives 
harmful  to  the  human  organism  ?''  but  it  is  encouraging  to  note  that 
the  consumer  is  better  pleased  with  table  condiments  so  preserved. 

The  testimony  offered  before  the  Parliamentary  Committee 
by  a  large  number  of  physicians  and  professional  men  is  interesting, 
and  is  remarkable  for  its  utter  lack  of  evidence  based  on  experi- 
mental investigation.  One  physician  after  another  is  called  before 
the  committee,  and  nearly  all  evidence  is  founded  on  mere  opinion 
or  the  result  obtained  by  abnormal  quantities  of  preservatives.  True 
investigation  had  not  been  made  by  many,  and  those  who  had  done 
any  experimental  work  did  not  produce  the  notes  and  data  to  prove 
their  claims.  The  following  testimony  was  offered  as  evidence  be- 
fore the  Parliamentary  Committee.  From  the  Blue  Book.  No. 
5745-46. 


238  canning  and  preserving  of  food  products. 

Mr.  Henry  Droop  Richmond. 

Question.  *'\Vith  regard  to  the  action  of  salicylic  acid  on 
enzymes,  is  your  opinion  of  that  subject  based  upon  what  you  have 
read  or  upon  what  you  have  done?  You  say  that  salicylic  acid  has 
an  action  on  the  enzymes." 

Answer.  "I  think  it  is  chiefly  based  upon  what  I  have  read. 
I  have  also  found  that  the  action  of  certain  enzymes,  diastase  for 
instance,  is  stopped  by  salicylic  acid.'' 

The  first  part  of  this  testimony  is,  indeed  very  like  that  of  many 
others.  Nearly  every  opposed  authority,  when  called  upon  to  ex- 
press his  opinion  as  to  the  action  of  salicylic  acid  on  enzymes,  al- 
most unhesitatingly  states  that  it  is  his  opinion  that  this  preserva- 
tive retards,  or  prevents  the  digestion  of  food  in  the  stomach  and 
when  pressed  as  to  the  basis  of  his  opinion,  like  every  one  of  his 
predecessors,  he  states  that  he  has  read  it.  Probably  the  author  of 
the  book  also  read  it  as  a  quotation  from  some  author  in  the  middle 
of  the  last  century. 

Digestive  processes  were  unknown  up  to  the  time  when  Theo- 
dore Schwann  in  1836  discovered  that  the  gastric  juice  contained 
pepsin,  and  it  was  only  three  years  previous  that  Payen  and  Perzos 
discovered  diastase  in  malt  extract.  All  literature  previous  to  the 
discovery  of  enzymes  and  organized  ferments  made  no  distinction 
between  them. 

This  idea  has  been  carried  down  in  various  scientific  works  ever 
since,  and  it  is  no  very  uncommon  thing  to  read  extracts  (which 
contain  the  essence  of  this  fallacy),  published  within  the  last  few 
years  by  authorities  who  have  never  given  this  subject  any  inves- 
tigation. 

Fermentation  is  a  term  very  greatly  misinterpreted;  it  is  re- 
peatedly treated  as  a  process  which  is  brought  about  by  bacteria, 
yeasts,  and  molds,  and  likewise  by  the  enzymes  of  digestion.  This 
is  a  great  error,  and  finds  expression  in  such  productions  as  the  fol- 
lowing : 

North  Dakota  Agricultural  Experiment  Station.  Bulletin  53. 
Page  119.  In  the  Minnesota  Dairy  and  Food  Commissioner's  Re- 
port for  1 901  this  statement  appears — preservatives  ''are  used  solely 
to  prevent  fermentation  and  since  the  processes  of  digestion  are 
fermentation  processes,  the  chemical  preservatives  must  work  an 
injury."     And  also. 

In  Bulletin  100  of  the  Kentucky  Agricultural  Experiment  Sta- 
tion, a  well-known  officer  of  the  State  Food  Commissioners'  Associ- 
ation says :  "The  strong  paralyzant  power  claimed  for  antiseptics 
is  sufficient  to  condemn  their  use  in  foods,  for  a  substance  which 
can  preserve  perishable  foods  under  any  conditions,  and  for  any 


PRESERVATIVES.  23& 

length  of  time,  will  also  affect  the  delicate  digestive  ferments  of  the 
stomach,''  and  he  quotes  a  government  authority  in  these  words : 
''There  is  no  preservative  which  paralyzes  the  ferments  which  cre- 
ate decay,  that  does  not  at  the  same  time  paralyze  to  the  same  ex- 
tent, the  ferments  that  produce  digestion.  .  .  .  The  very  fact  that 
any  substance  preserves  food  from  decay  shows  that  it  is  not  fit  to 
enter  the  stomach.'' 

I  was  much  surprised  that  the  authority  mentioned  in  Bulletin 
lOO  by  the  writer  of  that  article  should  have  made  such  a  statement, 
so  when  in  New  York  later  I  asked  the  gentlemen,  who  is  a  mem- 
ber of  the  Committee  on  Food  Standards,  if  he  had  been  quoted 
correctly,  and  he  stated  that  he  had  never  authorized  that  state- 
ment. It  is,  therefore,  up  to  our  Kentucky  friend  to  verify  his  quo- 
tation. 

So  far  as  I  am  aware  this  statement  did  not  appear  in  print 
until  Bulletin  loo  brought  it  out.  and  it  has  been  copied  and  changed 
to  fit  any  argument  opposed  to  preservatives  by  the  daily  press  and 
the  authorities  in  many  states.  In  the  light  of  modern  research  it 
is  ridiculous.  Any  investigator  could  prove  its  falsity  in  a  few 
hours'  experiment.  Every  physiologist  knows  that  hydrochloric 
acid  is  present  in  the  stomach  and  is  absolutely  necessary  in  the 
digestive  process.  Every  one  knows  that  it  is  an  antiseptic,  and  it 
is  frequently  combined  with  such  disinfectants  as  bichlorid  of  mer- 
cury to  increase  their  antiseptic  properties,  which  it  does,  from  50 
to  100  per  cent.  It  will  absolutely  prevent  the  multiplication  of 
bacteria  in  0.2  per  cent  solutions,  which  is  the  amount  found  in 
the  normal  stomach  during  digestion.  Yet  if  we  were  to  accept  the 
statement  quoted  in  Bulletin  100,  we  would  expect  to  have  our  di- 
gestive apparatus  completely  paralyzed  after  every  meal. 

The  bile  acids  are  antiseptics,  principally  taurocholic  acid, 
which  is  nearly  as  powerful  as  salicylic  acid,  so  affirmed  by  the 
following  authorities:  Lindenberger  (Bulletin  de  la  Societe  imp. 
des  naturalistes  de  Moscow,  1884)  :  also  Bunge's  Physiological  and 
Pathological  Chemistry,  second  edition,  pages  184  and  18.S,  quotes 
as  authority  Maly  and  Enrich  Monatshefte  (Chemistry,  Vol.  IV, 
page  89)  ;  also  Gley  and  Lambling  (Revised  biology  du  Nord  de  la 
France,  Vol.  I,  1886.) 

After  every  meal,  when  the  food  reaches  the  duodenum,  the 
bile  flows  into  it  carrying  the  antiseptic  taurocholic  acid,  and  not- 
withstanding the  statement  that  antiseptics  paralyze  the  ferments, 
the  digestion  is  stimulated  instead.  We  are  almost  ready  to  turn 
the  argument  quoted  by  our  Kentucky  writer  and  make  it  apply  in 
the  opposite  way,  thus,  "the  ferments  that  produce  digestion  are 
stimulated  by  antiseptics  in  the  same  proportion  that  the  organisms 
which  produce  decay  are  paralyzed." 


240  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

Prof.  Prescott,  of  the  University  of  Michigan,  is  quoted  in 
Bulletin  No.  53,  page  118,  of  the  North  Dakota  Agricultural  Sta- 
tion, as  follows :  "A  food  that  is  braced  against  decomposition  may 
be  found  to  be  braced  against  digestion."  I  am  quite  sure  that  the 
author  never  intended  this  to  be  garbled  in  this  manner  by  anyone, 
because  the  statement  has  an  element  of  truth  in  it.  Antiseptics  are 
not  used  to  completely  brace  foods  against  decomposition ;  indeed 
it  may  be  truly  said  that  manufacturers  of  table  condiments  such 
as  catsup,  Chili-sauce,  apple-butter,  peach-butter,  preserves,  jam, 
jellies,  etc.,  do  not  use  preservatives  to  completely  retard  decom- 
position, but  to  assist  the  sugar  and  the  container  to  arrest  fer- 
mentation until  such  foods  are  consumed.  It  is  well  know^n  that 
any  of  these  manufactured  products  will  spoil  within  a  certain  time 
after  the  original  package  is  opened.  Then  again,  some  foods  are 
chemically  changed  by  high  temperatures  so  that  they  become  in- 
digestible. Even  the  dark  brown  crust  of  bread  is  thus  changed  by 
heat  in  the  baking  process.  Milk  is  changed  to  some  extent  in  pas- 
teurization and  complete  sterilization.  Then  again  the  author 
quoted  uses  the  w^ords  ''may  be"  because  he  undoubtedly  recognized 
the  fact  that  his  statement  could  not  apply  in  all  cases  and  be  made 
to  do  duty  as  an  argument  against  preservatives  in  general. 

In  the  report  of  1892,  of  the  Committee  on  Interstate  and  For- 
eign Commerce  of  the  House  of  Representatives,  on  the  pure  food 
bills,  page  395,  it  is  stated  that  "Prof.  Mitchell,  of  Wisconsin,  con- 
siders any  active  antiseptic  necessarily  deleterious  to  health.  It 
retards  the  processes  of  the  stomach,  stopping  the  working  of  the 
normal  enzymes  or  ferments." 

In  the  light  of  our  experiments  with  salicylic  acid  and  pepsin, 
and  from  what  we  know  of  hydrochloric  acid  and  taurocholic  acid, 
such  statements  as  that  of  Prof.  Mitchell  are  ridiculous.  Here 
again  we  have  an  opinion  given  with  no  data  or  experiments  to 
prove  it  true,  and  that  opinion  is  on  record  to  be  quoted  as  an  es-  • 
tablished  fact  for  years  to  come.  Now  here  is  another  opinion 
which  is  directly  opposite  to  the  statement  made  by  Prof.  Mitchell. 
The  professor  of  Physiological  Chemistry  at  Yale  University  de- 
clares that  "Antiseptics  do  not  interfere  with  digestion"  (page  396 
of  the  same  report).  This  opinion,  coming  as  it  does,  from  such 
high  authority,  and  based  upon  personal  investigation,  as  we  know 
it  to  be,  throws  a  shadow  on  the  professor  from  Wisconsin.  Here 
is  another  opposing  opinion  by  Dr.  E.  H.  Starling,  Fellow  of  the 
Royal  College  of  Physicians  and  a  Fellow  of  the  Royal  Society. 
(Blue  Book  Report  of  the  Parliamentary  Committee  No.  6941,  page 
243-) 

Question.  "Wliat  have  vou  to  tell  us  as  regards  salicvlic 
acid?" 


PRESERVATIVES.  241 

Anszver.  ''Salicylic  acid  is  certainly  harmful,  less,  however, 
than  formalin.  In  an  acid  medium,  that  is  to  say,  the  medium  in 
vyhich  the  stomach  digestion  goes  on,  it  acts  as  an  antiseptic,  but  in 
the  stomach  where  it  is  acting  as  an  antiseptic,  it  also  prevents  the 
action  of  the  gastric  juice  and  stops  digestion  in  the  stomach. 
Clinically,  of  course,  one  knows  that  the  use  of  salicylic  acid,  especi- 
ally in  the  free  state,  is  apt  to  cause  symptoms  of  gastric  dyspepsia, 
pain  in  the  stomach,  and  stoppage  of  gastric  digestion,  etc." 

This  authority  states  in  the  beginning  of  his  testimony,  that 
he  had  made  physiological  experiments  with  salicylic  acid,  but  he 
does  not  state  what  they  were,  nor  how  they  were  made.  He  does 
not  state  whether  he  used  small  doses  or  whether  he  administered 
abnormal  quantities.  We  know  that  his  testimony  as  to  the  stop- 
page of  digestive  processes  in  the  stomach  is  absolutely  false,  if  he 
used  less  than  one  part  to  500,  because  we  have  demonstrated  by 
actual  experiment  that  digestive  processes  are  a  little  delayed  but  not 
entirely  stopped,  as  he  stated  the  case.  In  quantities  less  than  one 
to  500  the  delay  is  not  noticeable  and  in  either  case  the  delay  is  no 
greater  than  that  caused  by  many  substances,  such  as  common  salt, 
coffee,  tea,  etc.,  which  enter  the  stomach  in  a  mixed  diet. 

Clinically,  salicylic  acid  is  a  fine  remedy  for  fermentation, 
caused  by  living  organisms  in  the  stomach.  It  not  only  destroys  the 
bacteria,  but  actually  assists  the  gastric  juices  in  the  digestion.  Two 
cases  of  this  nature  have  come  under  my  personal  notice,  so  this 
would  indicate  that  the  testimony  of  Dr.  Starling  was  not  as  sci- 
entific as  it  should  have  been.  He  goes  on  to  say,  "When  the  food 
gets  down  to  the  intestines,  where  the  medium  is  alkaline,  and  where 
it  is  attacked  by  the  pancreatic  juice,  salicylic  acid  does  not  disturb 
digestion,  and  there,  of  course,  it  does  not  act  as  an  antiseptic." 
Late  investigation  has  shown  that  salicylic  acid  is  decomposed  in 
the  stomach  into  carbonic  acid  and  phenol,  which  are  carried  off 
by  the  urine. 

Prof.  William  Henry  Cornfield  was  called  before  the  com- 
mittee and  testified  as  follows :  "I  have  had  very  little  practical  ex- 
perience on  the  results  of  the  internal  administration  of  salicylic 
acid,  but  I  have  studied  the  effects  of  it  as  they  have  been  observed 
and  published  by  others."  This  statement  was  all  right,  and  he 
probably  said  just  what  all  the  other  witnesses  should  have  said, 
but  he  goes  on  with  his  testimony  just  as  if  he  had  made  a  deep 
physiological  and  chemical  research.  Note  his  answer  to  question 
5067  (page  177).  ''Suppose  a  person  were  taking  a  small  quantity 
of  salicylic  acid  day  by  day,  is  it  certain  he  could  get  rid  of  the 
whole  of  that  quantity  in  each  day  ?"  Answer — "I  do  not  think  it 
is."     Question  No.  5077  (page  177)  :  "Might  there  be  a  tendency 


242  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

to  accumulation?"  "Yes;  I  think  there  is  evidence  that  there  is 
a  tendency  to  accumulation  with  that  drug." 

As  we  stated  before,  there  is  no  evidence  to  show  anything  of 
the  sort,  and  it  is  well  known  that  salicylic  acid  and  some  other 
preservatives  are  almost  entirely  excreted  in  the  urine  and  perspira- 
tion. Like  all  chemical  work  this  test  shows  a  very  slight  amount 
which  cannot  be  accounted  for,  but  when  the  decrepancies  are  taken 
into  consideration  in  other  analytical  work,  it  is  a  fair  presumption 
that  the  unaccounted  per  cent,  is  a  chemical  decrepancy  due  to  in- 
accuracy in  analysis. 

I  have  been  impressed  while  reading  over  a  large  amount  of 
testimony  offered  on  various  preservatives,  that  only  rarely  is 
a  specific  quantity  named.  We  have  all  along  presumed  that  no 
greater  amount  of  preservative  should  be  used  for  physiological 
research  work  than  it  is  possible  for  anyone  to  actually  consume 
daily  in  food.  This  is  not  more  than  one  part  in  500  in  some  few 
articles,  and  not  more  than  one  part  in  2000  in  others.  It  is  hardly 
likely  that  anyone  would  eat  as  much  as  one  part  of  salicylic  acid  to 
1000  parts  of  general  food  and  fluids.  This  proportion  would  be  very 
high  indeed,  and  I  do  not  believe  that  such  an  amount  of  preserva- 
tives is  ever  used  continuously  by  anyone. 

Any  physician  could  say  that  certain  amount  of  preservatives 
would  prove  harmful,  and  the  same  thing  could  be  said  of  fire — 
a  certain  amount  of  heat  is  absolutely  necessary,  but  we  cannot 
reason  that  because  a  certain  amount  of  heat  will  burn  us  that  we 
should  not  use  heat — such  reasoning  would  be  absurd.  Heat  is 
good,  but  too  much  of  it  must  certainly  stop  digestion;  sugar,  salt, 
coffee,  tea,  etc.,  are  all  good  in  certain  amounts,  but  too  much  of  any 
will  stop  digestion,  therefore  any  testimony  which  does  not  specify 
a  fixed  amount  of  preservative  that  is  harmful  has  no  value  as  evi- 
dence, except  in  Pennsylvania. 

We  have  gathered  considerable  evidence,  as  our  readers  have 
found,  to  show  that  the  statements  by  various  authorities  on  the 
harmful  action  of  salicylic  acid  on  gastric  digestion  are  not  strictly 
in  accordance  with  facts.  We  have  yet  to  speak  of  the  argument 
advanced  by  several  investigators  to  the  effect  that  the  diastatic 
enzyme,  ptyalin  of  the  saliva,  is  stopped  by  such  preservatives  as 
salicylic  acid  and  benzoic  acid. 

In  order  to  answer  this  argument,  put  up  by  Prof.  H.  A. 
Weber  and  others,  we  must  outline  the  whole  digestive  process  and 
consider  the  nature  of  each  enzyme,  and  then  learn  how  wisely  Na- 
ture has  planned  the  whole  apparatus  so  that  disturbances  in  one 
quarter  do  not  necessarily  disturb  the  whole  process. 

The  ptyalin  or  diastatic  enzyme  of  the  saliva  is  secreted  in  an 
alkaline  fluid,  and  its    process  is   carried    on  in  an  alkaline    fluid. 


PRESERVATIVES.  243 

(Gamgee's  Physiological  Chemistry  of  the  Animal  Body  1893, 
pages  23-27). 

The  pepsin  or  albumen  digesting  enzyme  is  acid  and  requires 
the  presence  of  an  acid ;  even  small  quantities  of  alkaline  solution 
render  it  inert.     (Langley,  Journal  of  Physiology,  III.  page  246). 

The  trypsin  or  albumen  digesting  enzyme  of  the  pancreas 
"works  best  in  a  weak  alkaline  solution."  (Ferments  and  Their 
Action,  page  39,  Oppenheimer.)  Weak  acid  solutions  do  not  great- 
ly interfere  with  it,  but  any  solution  containing  as  much  acid  as  the 
gastric  juice  (estimated  at  0.2  per  cent.)  would  stop  this  enzyme. 

Now  this  is  certain,  therefore,  that  any  acid  or  alkaline  taken 
either  as  a  food  or  in  food,  must  have  some  influence  on  one  or  more 
of  these  enzymes.  It  is  the  acid  in  such  preservatives  as  salicylic  and 
benzoic  acids  that  has  a  retarding  influence  on  the  diastatic  enzyme 
of  the  saliva.  If  this  action  is  to  be  considered  harmful  by  the  op- 
ponents of  preservatives,  and  if  this  is  to  be  considered  as  a  reason 
for  prohibiting  preservatives,  then  the  same  objection  must  be  filed 
against  every  acid  food.  Lemonade,  phosphated  drinks,  acid  fruits 
of  all  kinds,  have  a  far  greater  influence  on  the  ptyalin  than  all  the 
added  preservatives  one  could  take  in  food,  as  it  is  now  prepared. 

The  pepsin  of  the  gastric  juice  is  retarded  by  all  alcoholic 
drinks,  beer,  wine,  etc.  "Beer,  even  when  containing  less  than  three 
per  cent,  of  alcohol,  has  a  strong  restrictive  action,  and  this  is  not 
to  be  ascribed  to  the  hops,  since  wine  has  the  same  effect."  (Fer- 
ments and  Their  Action,  page  96 ;  also  Buchner,  Arch,  f .  klin.  Med., 
XXIV.  537.) 

Tea  and  coffee  also  retard  the  action  of  the  pepsin  on  coagu- 
lated egg  albumen,  demonstrated  in  National  Canners'  Laboratory, 
June  "Index,"  1904.  Frazer  also  authorizes  this  conclusion. 
(Journal  of  Anatomy  and  Physiology,  XXXL,  page  469.) 

The  amount  of  salt  usually  taken  in  a  single  meal  retards  peptic 
digestion  as  much,  if  not  more,  than  all  the  preservatives  taken  in 
food  during  the  same  meal.  (National  Canners'  Laboratory  Re- 
port for  May  "Index,"  1904. 

Now  note  the  following:  "The  gall  normally  precipitates  the 
pepsin,  but  when  this  function  is  absent — e.  g.,  in  fistula — the  pep- 
sin penetrates  into  the  intestines  and  destroys  the  trypsin  to  a  more 
or  less  pronounced  extent,  and  thereby  the  digestion  of  the  albumen 
is  checked."     (Ferments  and  Their  action,  page  109.) 

The  arguments  based  on  the  ground  that  preservatives  should  not 
be  used  in  food,  because  they  restrict  or  retard  the  digesting  enzymes, 
grow  very  weak  in  the  face  of  the  facts  presented  here.  If  our 
physical  economy  were  so  delicately  constructed  and  so  easily  upset, 
we  would  all  be  constant  sufferers  from  indigestion.  Nature  has 
provided  a  way  to  neutralize  acids  and  salts  and  means  of  throwing 
off  unnecessarv  and  undesirable  substances. 


244  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

Since  it  has  become  known  among  scientists  that  the  preserv- 
atives commonly  used  in  food  products  are  largely  excreted  by  the 
kidneys,  a  claim  has  been  set  up  that  the  extra  amount  of  work 
which  is  forced  upon  these  already  over- worked  (?)  organs,  will 
necessarily  lay  the  foundation  for  kidney  diseases  of  various  kinds. 
In  Bulletin  No.  loo  of  the  Kentucky  Agricultural  Experiment  Sta- 
tion, page  loi,  speaking  of  preservatives,  the  writer  says  that  "they 
are  eliminated  by  the  kidneys  and  that  such  elimination  gives  rise 
to  various  forms  of  kidney  trouble." 

This  statement  is  made  without  any  quotation  from  medical 
literature  to  sustain  it,  and  the  reason  is  obvious,  since  no  such 
statement  is  thus  made,  so  far  as  I  am  able  to  find.  A  question 
was  once  asked  of  a  noted  physician,  "Within  the  last  few  years 
Bright' s  disease  has  increased,  and  is  it  not  possible  that  preserva- 
tives in  food  products  might  be  one  of  the  principal  causes?"  He 
answered  that  he  did  not  think  so,  because  there  are  several  other 
causes  at  work,  which  had  such  direct  responsibility  for  kidney  dis- 
eases, that  it  was  hardly  likely  that  preservatives  commonly  used 
in  food  products  were  in  any  way  contributory;  that  more  kidney 
diseases  were  directly  caused  through  invasion  by  micro-organ- 
isms, such  as  the  gonococcus  and  bacterium  pyocyaneus,  also 
streptococcus  and  staphylococcus  aureus  et  al;  and  since  such 
increase  of  gonorrhoeal  infections  has  been  reported  by  the  var- 
ious medical  societies,  kidney  diseases  may  be  traced  in  many  cases 
directly  to  this  malady.  It  is  reasonable  to  suppose  that  preserva- 
tives would  have  an  antiseptic  influence  on  micro-organisms  which 
invade  the  kidneys,  and  as  antiseptics  they  would  prove  beneficial, 
as  indeed  they  are,  and  are  prescribed  in  medicinal  doses  for  that 
very  purpose.  There  is  a  theory  that  antiseptics  taken  in  food  con- 
tinuously must  exert  an  irritating  influence  on  the  kidneys,  and 
eventually  must  cause  abnormal  changes,  followed  by  the  invasion 
of  micro-organisms. 

The  kidneys  are  endowed  by  nature  with  the  power  to  dis- 
solve all  kinds  of  irritating  and  poisonous  substances  from  the  blood 
stream,  and  afterwards  to  expel  them  through  the  urine,  so  it  is  not 
a  fair  presumption  to  suppose  that  they  are  injured  because  certain 
substances  are  supposed  to  have  irritating  properties.  We  should 
naturally  expect  to  find  some  evidence  of  irritation  on  the  mucous 
membrane  of  the  stomach  prior  to  any  injury  of  the  kidneys.  In 
cases  of  Bright' s  and  kindred  diseases,  the  post  mortems  often  re- 
veal the  fact  that  the  stomach  is  normal  in  every  way,  and  this 
would  seem  to  prove  that  hyperplastic  processes  were  caused 
through  invasion  by  bacteria. 

There  is  very  little  medical  testimony  to  prove  that  diseases  of 
the  kidneys  are  due  to  overwork  in  eliminating  substances  which 


PRESERVATIVES.  245 

pass  unchanged  through  the  body.  One  writer  has  mentioned  salt 
as  a  substance  excreted  by  the  kidneys.  This  chemical  passes 
through  the  body  as  sodium  chlorid  and  does  not  cause  any  ab- 
normal processes  of  kidney  degeneration.  Another  writer  speaks 
of  water  as  a  substance  which  passes  unchanged  through  the  body 
and  is  excreted  by  the  kidneys  without  any  injury  to  them;  there- 
fore, it  is  not  a  sound  argument  that  because  a  substance  passes 
unchanged  through  the  body,  it  must  overwork  the  kidneys. 

There  are  probably  no  organs  of  the  human  body  more  ad- 
mirably capacitated  for  work  than  the  kidneys.  There  are  two 
of  them,  and  ordinarily  there  is  very  little  more  than  enough  work 
for  one ;  the  other  is  always  ready,  however,  to  assist  in  the  elimina- 
tion of  foreign  substances  from  the  blood  stream.  Some  experi- 
ments have  been  made  with  animals  to  determine  working  capacity 
of  the  kidneys,  and  it  was  proven  that  three-fourths  of  a  kidney 
could  be  cut  away  before  any  serious  consequences  could  be  detected. 
(Albutt's  System  of  Medicine,  Vol.  IV.,  p.  318.) 

Americans  consume  large  quantities  of  nitrogenous  foods 
and  an  unusual  amount  of  work  is  forced  upon  the  kidneys  in  order 
to  expel  the  nitrogen,  but  there  are  a  number  of  cases  on  record 
where  human  beings  have  lived  for  many  years  with  only  one  kid- 
ney, which  had  to  do  all  the  work  devolving  upon  these  organs. 
This  would  indicate  that  any  person  having  two  normal  kidneys 
would  not  be  seriously  overworking  them  by  allowing  them  to  ex- 
pel a  very  small  quantity  of  such  preservatives  as  salicylic  or  benzoic 
acid. 

The  kidneys  must  excrete  the  uric  acid  from  the  body,  and 
salicylic  acid  is  helpful  in  its  removal,  and  for  this  reason  the  pre- 
servative is  given  as  a  remedy  for  rheumatism.  (Practical  Thera- 
peutics-Hare, page  341.) 

Salicylic  acid  unites  with  ^^lycin,  forming  salicyluric  acid; 
also,  benzoic  acid  unites  with  glycin,  forming  hippuric  acid,  and  both 
of  these  antiseptics  are,  therefore,  helpful  in  assisting  the  kidneys 
to  expel  the  glycin,  or  as  it  is  commonly  called  glycocoll,  or  amido- 
acetic  acid.      (Cushny-Pharmacology  and  Therapeutics,  page  417.) 

In  the  London  Lancet  of  November  25,  1899,  P^?^  1^427, 
Cushny  rather  opposed  salicylic  acid,  because  it  was  excreted  from 
the  body  in  a  form  unlike  any  product  of  normal  urine,  but  he  did 
not  oppose  benzoic  acid  because  it  was  excreted  as  hippuric  acid, 
which  is  found  in  normal  urine. 

Dr.  R.  G.  Eccles  has  pointed  out  the  false  reasoning  in  this, 
however,  because: 

Salicyluric  acid  is  salicylic  acid  plus  glycin. 

Hippuric  acid  is  benzoic  acid  plus  glycin. 

In  other  words,  there  is  very  little  difference  between  the  two, 
salicylic  acid  being  simply  equivalent  to  hippuric  acid  plus  water. 


246  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

"As  glycin  or  glycocollic  acid  is  a  precursor  of  urea,  its  remov- 
al by  means  of  salicylic  or  benzoic  acid,  aids  the  body  in  getting 
rid  of  its  waste  product."  (American  Text-book  of  Physiology, 
page  981,  also  Foster's  Text-book  of  Physiology,  page  539.) 

It  would  seem  from  this  that  preservatives  such  as  these  are 
beneficial  rather  than  detrimental.  Normal  kidneys  cannot  be  in- 
jured by  them,  and  since  they  are  antiseptic  by  nature,  it  is  fair  to 
presume  that  any  one  who  is  suffering  with  kidneys  diseased  by 
invading  bacteria  must  be  benefitted  by  the  preservatives  which  have 
inhibitory  influence  upon  bacterial  life,  providing  that  such  antisep- 
tics  are  not  taken  in  doses  large  enough  to  be  irritating  or  to  cause 
cellular  metabolism. 


PRESEIRVATIVES.  247 

CHAPTER  VIII. 

Preservatives — Continued 

Experiments  With  Preservatives  and  Other  Substances  to  Deter- 
mine Their  Effect  on  Peptic  Digestion.  Physiological  and  Path- 
ological Research  Work  With  Animals  Fed  on  Salicylic  and 
Benzoic  Acids.     Post  Mortems.     Conclusions. 


E^XPKRIMKNTS  WITH  PEPSIN. 

A  number  of  flasks  were  prepared,  using  the  formula  for  test- 
ing the  activity  of  pepsin  given  in  the  Pharmacopoea.  A  series 
of  experiments  were  made  as  follows : 

Plask  No.  /.— 

I2j^  grams  hard  boiled  white  of  tgg. 
125  c.  c.  pure  water. 
0.2  per  cent,  hydrochloric  acid. 
0.005  gram  of  pepsin. 

Plask  No.  11. 

Just  the  same  as  No.  i  with  the  addition  of  %  gram  of  salicylic 
acid  dissolved  in  water. 

Flask  No.  III.— 

Just  the  same  as  No.  i  with  the  addition  of  %  gram  of  com- 
mon salt. 

Flask  No.  IV.— 

Just  the  same  as  No.  i  with  the  addition  of  one  loopful  of 
Bacillus  Vulgaris  and  one  loopful  of  a  bacillus  found  in  corn. 

All  these  flasks  were  kept  for  six  hours  in  the  incubator  at  a 
temperature  of  150°  F.  and  agitated  frequently. 

No.  I  showed  only  a  few  flakes,  and  all  the  rest  had  a  small 
quantity  of  ^gg  still  undigested.  After  two  or  more  hours  these 
were  just  like  No.  i. 

This  proves  that  salicylic  acid  in  very  strong  solutions  does  not 
impede  digestion  more  than  other  substances  consumed  in  a  mixed 
diet,  common  salt  retarding  fully  as  much  as  the  acid.  Ordinary 
bacteria  taken  at  meal  time  have  the  same  retarding  influence,  al- 
though the  amount  of  hydrochloric  acid  used  prevented  them  from 
propogating. 


248  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

In  order  to  test  the  retarding  influence  of  various  substances  in 
comparison  with  preservatives,  a  number  of  flasks  were  prepared 
as  follows : 

Flask  No,  I— 

125  cubic  centimeters  of  water. 

T2.5  grams  of  hard  boiled  white  of  o^gg,  finely  divided. 

0.005  gram  of  pure  pepsin. 

0.2  per  cent  hydrochloric  acid. 

Plask  No.  II— 

Just  the  same  as  No.  I  with  the  addition  of  0.25  gram  of  pre- 
servative commonly  used  in  food  products.     Benzoic  Acid. 

Plask  No,  III— 

Just  the  same  as  No.  I  with  the  addition  of  0.25  gram  of 
ground  coffee. 

Flask  No.  IV— 

Just  the  same  as  No.  I  with  the  addition  of  0.25  gram  of  green 
tea. 

Flask  No.  V— 

Just  the  same  as  No.  I  with  the  addition  of  0.25  c.  c.  of  absolute 
alcohol. 

Flask  No.  VI— 

Just  the  same  as  No.  I  with  the  addition  of  o.io  gram  of  salicy- 
lic acid,  o.io  gram  of  coffee  and  o.io  gram  of  tea. 

These  were  placed  in  the  incubator  and  kept  for  six  hours  at 
105°  F.  and  frequently  shaken.     The  results  are  most  interesting. 

In  flask  No.  5  the  coagulated  egg  albumen  dissolved  first ;  that 
in  No.  I  w^as  second;  No.  VI  was  third  with  just  a  few  flakes  un- 
dissolved; No.  II  was  fourth;  No.  IV  was  not  complete;  and  No. 
Ill  was  decidedly  retarded,  fully  half  of  the  egg  remained  undi- 
gested. No.  VI  was  the  most  interesting  from  the  fact  that  it  con- 
tained three  substances  which  are  claimed  to  retard  digestion.  This 
flask  contained  coffee,  tea  and  salicylic  acid  and  complete  digestion 
of  the  egg  albumen  followed  the  typical  experiment  represented  in 
flask  No.  I.  It  can  be  explained  in  but  one  way — i.  e.,  that  the 
small  quantity  of  salicylic  acid  used  acted  as  a  stimulant. 

Flask  No.  V,  containing  the  absolute  alcohol,  was  the  first  to 
complete  the  digestion  of  the  egg  albumen,  and  we  must  conclude 
that  a  very  small  per  cent  of  alcohol  stimulates  digestion,  while  we 
know  that  when  the  per  cent  is  increased  to  3  it  greatly  retards  di- 
gestion.     (Buchner,  Arch.  f.  Klin.  Med.  XXIX-537.) 


PRESERVATIVES.  249 

We  find  that  salicylic  acid  in  minute  quantities  stimulates  di- 
gestion. This  is  true  of  all  acids.  (Oppenheimer — Ferments  and 
Their  Action,  page  97.) 

In  the  proportion  of  i  to  500  it  retards  digestion  slightly,  just 
about  as  much  as  common  salt,  and  in  larger  amounts  it  will  pos- 
sibly interfere  with  digestion.  The  conclusion  to  be  drawn  is  that 
the  amount  of  any  substance  is  a  very  important  factor  in  deter- 
mining its  action  on  digestive  processes.  Certain  quantities  may 
be  positively  beneficial,  while  increased  amounts  may  be  injurious. 

FEEDING   PRESERVATIVES  TO   ANIMAI^S,    POST    MORTEM,   AND   PATHO- 
I^OGICAI,  ANAI^YSES  OE  INTERNAI.  ORGANS. 

One  of  the  arguments  advanced  by  the  opponents  of  food  pre- 
servatives is  the  opinion  of  many  eminent  physicians  that  the  deli- 
cate mucous  membrane  of  the  stomach  will  become  irritated  and 
inflamed,  and  thereby  be  injured  to  a  greater  or  less  degree,  if  pre- 
servatives, and  particularly  salicylic  acid,  be  taken  continuously  in 
food  and  drink.  This  objection,  although  founded  as  we  believe 
on  nothing  but  mere  speculation,  would  seem  to  be  a  very  strong 
one  indeed.  We  all  know  how  easily  the  stomach  responds  to  the 
action  of  chemicals  and  even  to  the  influence  of  the  mind.  The 
cells  of  the  mucous  membrane  are  very  sensitive  to  any  influence 
not  exactly  in  accord  with  normal  conditions.  Even  the  state  of 
the  nerves  of  the  body  has  an  influence ;  nauseating  odors  and  dis- 
gusting sights  are  influences  which  completely  upset  the  stomach. 
Anger,  passion,  joy,  sorrow  and  other  influences  of  the  mind  act 
upon  the  cells  of  the  mucous  membrane,  and  for  a  time  the  stomach 
cannot  perform  its  work  normally.  We  all  know  that  certain 
drugs,  medicines  and  improper  food  will  cause  stomach  derange- 
ment for  a  certain  time;  some  medicines  completely  upset  the  nor- 
mal condition,  others  stimulate  the  action  of  the  enzymes,  and  still 
others  cause  inflammation  of  the  stomach.  Some  physicians  say. 
then,  it  is  a  very  probable  conclusion  that  preservatives  will  irritate 
the  stomach,  and  this  argument  above  all  others  is  made  to  do  duty 
as  a  strong  reason  why  these  chemicals  should  not  be  permitted  in 
foods.  There  are  a  number  of  cases  on  record  where  persons  have 
purposely  taken  various  quantities  of  one  preservative  or  another 
in  daily  doses,  and  we  have  very  favorable  testimony  to  the  efl^ect 
that  no  evil  results  followed,  although  in  many  cases  abnormal 
amounts  were  taken.  When  abnormal  quantities  of  salicylic  acid 
are  taken  the  warning  is  sounded  by  a  ringing  or  buzzing  sensation 
in  the  ears,  similar  to  the  effects  felt  after  taking  quinine  in  large 
doses.  It  is  a  remarkable  fact  that  no  discomfort  has  been  felt  from 
taking  stated  quantities  of  salicylic  acid  below  the  amount  which 
will  cause  a  ringing  sensation  in  the  ears. 


250 


CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


Diligent  search  has  been  made  for  the  names  of  any  persons 
who  would  give  evidence  that  they  had  experienced  any  ill  effects 
from  stated  doses  of  salicylic  acid  under  the  amount  that  will  cause 
the  ringing  sensation  or  fullness  in  the  head.  No  such  amount  of 
this  preservative  is  ever  used  in  food  products.  There  are  only 
three  or  four  products  which  require  more  than  i.iooo  of  any  pre- 
servative, and  this  amount  is  very  small  in  proportion  to  the  full 
meal.  Such  condiments  as  require  a  preservative  are  used  only 
sparingly  at  meal  time;  as  a  rule  they  are  used  to  improve  other 
food  or  make  it  more  palatable.     No  one  would  make  an  entire  meal 


Plate  70.     Four  Guinea  Pigs  selected  as  controls. 


...jm- '  '•■^' v^^iB^ 

I^^^^StoMJ^^H^^I^^  lIB^ 

.^  \  ^  j^ 

f^^^m^ 

^'['''                                                      •''  ""f       ^ 

Plate  71.     Six  Guinea  Pigs  and  Two  Rabbits. 
Whose  food  was  saturated  with  salicylic  acid. 


of  tomato  catsup  or  chili-sauce;  only  a  small  quantity  is  taken  on 
cold  meat,  on  oysters  or  in  soup.  Very  few  persons  would  use 
these  condiments  at  more  than  one,  possibly  two  meals  per  day,  con- 
sequently the  amount  of  such  preservative  as  is  used  to  keep  them 
in  an  unfermented  condition  w^ould  be  very  small  indeed. 

We  have  heard  several  authorities  say  that  if  preservatives 
were  used  only  in  such  food  as  we  have  specified  there  would  pos- 
sibly be  very  little  objection  to  them,  but  the  claim  is  made  that  per- 
haps nearly  all  the  prepared  food  of  various  kinds  contained  pre- 


PRESERVATIVES.  251 

servatives,  and  in  such  amounts  would  prove  dangerous  and  poison- 
ous to  the  human  organism;  also  that  if  preservatives  were  per- 
mitted in  one  kind  of  food  it  would  be  difficult  to  draw  the  line  and 
prevent  their  employment  in  all  foods.  Then  the  argument  fol- 
lows that  in  such  amounts  they  would  injure  the  mucous  membrane 
of  the  stomach  and  other  internal  organs. 

It  is  easy  to  assume  that  certain  effects  will  follow  certain 
causes,  but  it  is  a  very  difficult  matter  to  disprove  the  assumption, 
so  when  a  large  number  of  physicians  assert  positively  that  the  muc- 
ous membrane  of  the  stomach  will  be  injured  by  salicylic  acid  in 
the  amounts  ordinarily  used  in  food  products,  the  amount  of  work 
required  to  overthrow  such  an  assumption  is  large,  and  the  technique 
employed  in  conducting  the  experiments  is  difficult,  requiring  special 
skill  and  a  thorough  knowledge  of  pathology.  To  this  end  a  series 
of  experiments  were  conducted  with  animals,  and  Dr.  W.  H.  In- 
gram, professor  of  pathology  in  the  West  Penn  Medical  College, 
and  Dr.  R.  G.  Burns,  pathologist  and  bacteriologist  for  the  City  of 
Allegheny,  Pa.,  undertook  the  pathological  part  of  the  work.  A 
number  of  guinea  pigs  w^ere  fed  a  weighed  amount  of  salicylic  acid 
daily.  The  acid  used  was  the  synthetical  product,  that  which  has 
been  used  so  extensively  in  food.  yYz  milligrams  of  the  acid  were 
mixed  in  a  breakfast  cereal  with  milk,  which  amount  was  fed  daily 
to  each  pig.  This  amount  was  found  too  large  because  the  ani- 
mals would  not  eat  it  unless  forced  to  do  so  by  hunger,  so  the 
amount  was  cut  down  to  5  milligrams.  The  only  food  taken  by 
the  pigs  outside  of  the  prescribed  diet  was  grass,  which  was  fed  to 
them  liberally.  Comparing  the  weight  of  a  guinea  pig  with  that 
of  an  average  man,  which  is  as  i  to  100  or  i  to  150,  the  same  pro- 
portion of  acid  would  be  from  7j4  to  10  grains  daily  for  a  man,  and 
this  amount  of  preservative  would  be  sufficient  to  inhibit  the  growth 
of  micro-organisms  in  16  to  24  ounces  of  solid  food  in  proportion  of 
1  to  1000.  This  amount  of  preservative  is  far  in  excess  of  the 
amount  taken  in  food  daily  by  any  person,  but  it  represents  an  ex- 
treme case,  but  nevertheless  one  which  might  be  possible.  It  is 
possible  that  in  rare  cases  a  person  might  consume  such  a  quantity 
of  certain  foods  and  drinks  that  he  would  take  as  much  as  10  grains 
or  more  in  a  single  day,  but  this  would  not  be  continued  daily. 
Physicians  prescribe  sodium  salicylate  in  30  grain  doses  three  times 
daily  for  rheumatism.  In  this  there  would  be  about  22  grains  of 
pure  salicylic  acid  in  each  dose,  consequently  60  grains  daily  for  a 
limited  time  would  not  endanger  a  person.  Therefore,  if  any  per- 
son should  happen  to  take  more  than  10  grains  at  a  single  meal  or 
in  one  day,  he  would  not  suffer  any  special  inconvenience. 

We  are  certain  that  the  experiment  conducted  with  the  guinea 
pigs  on  a  basis  of  5  milligrams  of  salicylic  acid  daily  is  sufficiently 
broad  to  cover  all  cases. 


252  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

The  experiments  were  conducted  with  guinea  pigs  in  prefer- 
ence to  any  other  animals  for  several  reasons.  There  are  no  ani- 
mals which  live  on  a  diet  exactly  the  same  as  a  human,  and  in  select- 
ing animals  we  must  not  select  any  such  as  the  dog  or  cat  which  eat 
food  partially  decomposed,  because  the  stomachs  of  such  animals 
are  not  as  sensative  to  poisons  as  the  human.  The  stomach  of  the 
guinea  pig  is  sensitive  to  poisons  and  cannot  tolerate  certain  foods. 
Even  milk  is  not  properly  digested  unless  mixed  with  cereal.  An- 
other reason  for  selecting  guinea  pigs  is  that  they  are  herbivorous. 
They  are  accustomed  to  a  vegetable  diet,  and  since  nearly  all  the 
food  products,  in  which  a  preservative  is  used  are  made  from  fruits 
and  vegetable,  these  animals  seem  to  be  well  suited  for  the  experi- 
ments. They  are  cheap,  easily  handled  and  are  not  very  large,  so 
that  every  advantage  may  be  claimed  for  their  selection. 

The  first  series  includes  two  pigs  fed  on  5  milligrams  of  salicy- 
lic acid  mixed  with  cereal  daily,  and  one  pig  fed  just  the  same 
amount  of  cereal,  but  no  acid  (this  one  was  used  as  a  control).  By 
having  controls  we  are  able  to  determine  any  physiological  differ- 
ences, and  the  post  mortem  comparisons  are  quite  valuable  and  nec- 
essary. 

When  these  experiments  were  begun  the  pigs  were  not  full 
grown  and  none  of  them  showed  any  signs  of  pregnancy.  One  of 
this  series  was  a  female  and  pregnant,  which  became  apparent 
toward  the  end  of  the  period  from  the  increased  weight  and  shape 
of  the  animal,  but  it  was  decided  to  learn  if  any  pathological  changes 
could  be  found  in  such  cases,  therefore  she  was  submitted  for  an- 
alysis. 

SERIES  NO.   (i) 

The  weights  of  these  three  guinea-pigs  were  taken  every  other 
day,  the  results  of  which  are  here  appended  in  a  table. 


WEIGHT  OF   ANIMAlvS   IN   OUNCES. 

DATE 

•>      >      > 
<      <      < 
S     S      S 

14       16       18 

20       22       24       26       28       30        2         5         7        9 

z 

D 
11 

z       z 

13       15 

Brown  Female 
Pregnant 

...18^  1834  18J< 

18K   19J^   19%  20Ji   20%   20%   20'^   21^   213%   21% 

22 

22%     24 

Brown  Male  ..... 

...\1%   17^8     18 

18%     19       19     19%   19%   18%   18%   19^   19J^   m/2 

19% 

19%  20^ 

White  (Male 
Control) 

...      X           X           X 

X        17     17%  18^     18     11%  17%  18%  18%  19% 

19Ji 

19%   20% 

The  table  increase  in  weight  for  all  three  guinea-pigs  up  to 
May  30,  when  for  some  unaccountable  reason  they  all  lost  and  this 


PRESERVATIVES.  263 

was  not  regained  until  five  days  later.  This  decrease  in  weight  was 
true  of  the  control  as  well  as  of  the  others,  indicating  that  the  salicy- 
lic acid  was  not  the  cause.  In  the  thirty  days  guinea-pig  No.  ( i ) 
had  gained  5J^  ounces;  No.  (2)  had  gained  5  ounces;  No.  (3)  the 
control,  gained  only  2/i  ounces  in  the  24  days. 

All  three  animals  were  then  given  to  Dr.  W.  H.  Ingram  for 
pathological  examination.  He  is  an  eminent  authority  on  pathology 
and  the  following  is  his  report : 

DR.  Ingram's  report. 

Pittsburg,  Pa.,  July  15,   1904. 

I  here  append  analyses  of  guinea  pigs,  June  15,  1904,  marked 
Pigs  I,  2  and  3,  Series  i. 

I.       GENERAI,   APPEARANCE. 

All  these  are  well  nourished  animals  and  very  active. 
Pig  No.  I,  female,  pregnant,  near  full  term.     Color,  red  and 
white. 

Pig  No.  2,  male.     Color,  black  and  brown. 

Pig  No.  3,  male,  marked  "Control."     Color,  white  and  yellow. 

II.      POST-MORTEM.       APPEARANCES. 

All  three  animals  were  killed  at  the  same  time.  Examination 
shows  as  follows:     Animals  still  warm. 

I.  Pig  No.  I.  Subcutaneous  fat  normal.  Axillary  and  in- 
guinal lymph  glands  normal.     Muscle  normal. 

I.     Abdominal  Cavity — 

1.  Stomach  partially  filled  with  grass  and  macerated  food. 
Emptied,  and  musculature  contracted  normally.  No  change  in 
color. 

2.  Intestine — Normal.  Various  portions  contain  faecal  mat- 
ter of  character  found  in  parts. 

3.  Liver — Normal  in  position  and  size. 

4.  Gall  Bladder — Normal ;  partially  filled  with  bile. 

5.  Pancreas — Normal  in  size  and  position. 

6.  Spleen — Normal  in  size  and  position. 

7.  Kidneys — -Normal  in  size  and  position. 

8.  Suprarenals — Normal  in  size  and  position. 

9.  Uterus — Contains  three  pigs.  Estimated  about  one  week 
short  of  full  term.     Pigs  normal.     Placenta  normal. 

10.  Bladder — Partially  emptied.     Urine  contained,  normal. 

11.  Mesentary  and  Glands — Normal. 


254  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

2.     Thoracic  Cavity — 

1.  Lungs — No  pathological  changes  either  in  position  or  size. 

2.  Heart — Normal  in  size  and  position.  Right  side  partially 
distended  with  blood.     Muscle  color  normal. 

II.     Pig  No.  2— 

I.  Subcutaneous  fat  normal  in  amount.  Axillary  and  lymph 
glands  normal  in  size. 

1.  Abdominal  Cavity^ — 

1.  Stomach — Partially  filled  with  well  macerated  and  par- 
tially digested  food,  principally  grass.  Emptied,  and  muscle  wall 
contracted  normally.     Color  not  altered. 

2.  Intestine — No  changes  from  normal  in  size  or  contents. 

3.  Liver — Normal  in  size  and  position. 

4.  Gall  Bladder — ^Distended  with  bile. 

5.  Pancreas — Normal  in  size  and  position. 

6.  vSpleen — Normal  in  position,  color  and  size. 

7.  Kidneys — Normal  in  position,  color  and  size. 

8.  Suprarenals — Normal  in  position,  color  and  size. 

9.  Testes — Normal  in  position,  color  and  size. 

10.  Bladder — Empty  and  firmly  contracted. 

11.  Mesentery  and  Glands — Show  no  pathological  changes. 

2.  Thoracic  Cavity. 

1.  Lungs — No  changes  appreciable. 

2.  Heart — In  position,  color  and  size  normal.  Right  side 
partially  filled  with  blood. 

ni.     Pig  No.  3- 

This  animal,  marked  "Control  No.  i"  was  a  normal,  healthy 
male,  and  careful  examination  failed  to  show  any  pathological  pro- 
cesses.   All  organs  were  inspected  as  in  Pigs  Nos.  i  and  2. 

III.       MICROSCOPIC  EXAMINATION. 

I.     Technique. 

The  organs  from  these  animals  were  placed  in  4  per  cent  solu- 
tion of  Formaldehyde  for  fixation.  This  step  was  completed  while 
the  parts  were  still  warm.  The  stomach  and  intestines  were  spread 
out  flat.  Other  solid  organs  were  cut  into  slices  about  2  m.  m.  thick. 
After  remaining  in  this  fixing  fluid  for  about  40  hours,  they  were 
placed  in  running  water  for  24  hours,  and  then  in  80  per  cent  alco- 
hol for  preservation. 


PRESERVATIVES.  255 

Parts  of  each  solid  organ,  measuring  2  c.  m.  long  by  i  c.  m. 
wide  and  i  m.  m.  thick  were  then  placed  in  alcohols  of  90  per  cent, 
95  per  cent  and  "100  per  cent"  ("absolute  alcohol,"  99.8  per  cent 
— Squibb)  for  24  hours  for  each  per  cent.  The  wall  of  the  stomach 
was  cut  in  sections  having  about  the  same  surface  area,  and  includ- 
ing all  the  coats.  The  sections  of  the  stomach  were  placed  in  the 
ascending  alcohols  with  those  from  the  solid  organs. 

From  the  alcohols  they  were  immersed  in  a  mixture  of  equal 
parts  of  99.8  per  cent  alcohol  and  ether  for  a  period  of  24  hours. 

The  imbedding  was  in  celloidin.  Two  solutions  were  used. 
One,  thin  celloidin,  in  which  the  sections  remained  48  hours,  and  the 


Plate  72 

Photomicrograph  showing  glands  of  the  mucous  membrane  of  the  stomach,  cardiac  end.     There  is  no  evi- 
dence of  degenerative  changes.     Guinea  pig  No.  1.     Spencey  2  m.m.  objective.     IX  compensating  eyepiece. 

second,  thick  celloidin  (practically  a  saturated  solution  in  alcohol 
and  ether),  in  which  they  remained  48  hours.  They  were  next 
placed  in  "wood  fiber"  blocks,  hardened  for  24  hours  in  80  per  cent 
alcohol,  and  cut  on  a  "Minot  Perusian  Microtome,"  2  to  3-micra 
thick. 

Staining  was  produced  by  the  Hematoxyln  and  Eosine  method,, 
and  sections  were  mounted  in  Balsam. 

All  sections  stained  easily,  with  sharp  differentiation. 

2.     Results  of  Examination — 
I.     Pig  No.  I— 

I.     Stomach.      (Section  G.  P.  527  and  526.) 


256 


CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


Mucosa,  (i).  Surface  epithelium — Does  not  show  any 
pathological  changes.  Nuclei  are  sharph^  stained  and  normal  in 
size  and  position.  Cell  protoplasm  does  not  show  any  evidence  of 
degenerative  changes,  staining  evenly. 


Plate  73 

Photomicrograph  showing  mucous  membrane  of  the  stomach  of  guinea  pig  No.  1.  Cardiac  end.  The 
•cells  are  all  normal  and  show  the  nuclei  plainly.  Photographed  through  the  microscope,  using  a  2  m.m. 
objective  and  6X  compensating  eyepiece. 

(2)  Glands — These  are  normal  in  shape  and  arrangement. 
No  changes  can  be  seen  in  the  lumen  or  the  cells  forming  the  gland. 
The  central  cells  show  no  changes,  staining  evenly.  In  the  cardiac 
glands  the  Parietal  Cells  are  very  sharply  defined,  nuclei  staining 
evenly,  and  the  protoplasm  showing  no  evidences  of  degeneration. 
The  interglandular  connective  tissue  does  not  show  any  tendency 
to  leukocytic  or  round  cell  infiltration,  nor  does  it  show  any  other 
evidence  of  either  hyperplasia  or  inflammation.  The  vessels  of  the 
mucosa  are  normal.     The  lenticular  glands  are  also  normal. 

No  changes  either  of  an  inflammatory  or  degenerative  char- 
acter can  be  seen  in  the  other  coats. 
.     2.     Spleen.     (Section  G.  P.  528.) 

This  organ  shows  no  lesions.  The  capsule  is  not,  in  any  part 
examined,  thickened,  or  shows  signs  of  inflammation.  Trabeculae 
also  normal.  Malpighian  bodies  show  no  evidences  of  any  degener- 
ative changes.  Pigment  in  sinuses  and  cells  not  affected.  Blood 
vessel  walls  normal. 

3.     Heart.     (Section  G.  P.  524.) 


PRESERVATIVES. 


257 


Plate  74 

r-—      Photomicrograph — Suprarenal    and    adjoining    adipose    tissue,    showing   capsule,    cortex    and    part    of 
medulla.     2  m.m.  objective  and  IX  compensating  eyepiece. 


Plate  75 

Photomicrograph — Spleen,     Showing  malpighian  bodies.    16  m.m.  objective  and  6X  compensating   eyepiece. 


258 


CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


(i)  Endocardium — No  evidence  of  degeneration  nor  of  in- 
flammation. 

(2)  Myocardium — Muscle  Fibers — Nuclei  normal,  striations 
distinct.  No  changes  in  intercellular  substance.  The  interstitial 
connective  tissue  normal  in  amount.  No  evidences  of  any  inflam- 
matory or  degenerative  process  can  be  seen. 

(3)  .  Pericardium — This  does  not  show  any  pathological  pro- 
cess. 


Plate  76 

Photomicrograph  showing  the  involuntary  muscles  of  the  heart  of   guinea  pig   No.  2.     The  striations  are 
well  marked   and  the   cells  show   no  degenerative  changes.     2  m.m.  objective  with  12X  compensating  eyepiece. 


4.  Kidneys.      (Sections  G.  P.  531^  and  531^.) 

Both  kidneys  were  examined.  The  malpighian  bodies  do  not 
show,  either  in  the  capsule  of  Bow^man,  nor  in  the  glomerulus,  and 
evidences  either  of  an  inflammator}^  or  degenerative  character.  The 
same  may  be  also  said  of  the  tubule,  from  the  neck  to  the  termina- 
tion. The  lumen  of  the  tubule  is  at  no  place  filled  with  unnatural 
products. 

The  interstitial  connective  tissue  is  also  normal.  Blood  ves- 
sels show  no  changes  of  any  type. 

5.  Suprarenals.     (Section  G.  P.  532.) 

This  shows  no  evidence  of  any  pathological  character  either  in 
the  capsule,  connective  tissue,  cortex  or  medullae. 

6.  Pancreas.     (Section  G.  P.  529.) 


PRESERVATIVES.  259 

This  organ  is  also  normal.  The  bodies  of  Langerhaus  do  not 
show  any  evidences  of  pathological  processes.  The  cells  of  the 
glands  stain  clearly^  evenly  and  are  of  normal  size  and  shape.  Vari- 
ous sections  show  the  same  normal  character. 

I.     Placenta  and  Uterus.      (Section  G.  P.  530.) 
Examination  shows  a  normal  placenta.     The  uterine  wall,  as 
well  as  the  placental  attachment,  show  no  disease  conditions  what- 
ever. 

II.     Pig  No.  2— 

This  pig  shows  characters  in  no  way  differing  excepting  those 
of  sex  from  those  described.  Taking  the  organs  in  the  same  order 
they  show  the  following: 


Plate  11 

Photomicrograph  of  a  section  of  the  pancreas  of  guinea  pig  No.  1,  showing  lobules,  centro-acinar  and 
secretory  cells.  There  is  no  evidence  of  pathological  changes.  Magnified  by  2  m.m.  objective  and  IX  compen- 
sating eyepiece. 

1.  Stomach.      (Sections  536  and  537.) 

Surface  epithelium  normal,  nuclei  and  protoplasm  staining 
evenly  and  typically. 

The  glands  do  not  present  any  alterations  in  shape  or  position. 
The  "central"  and  "parietal"  cells  staining  in  characteristic  manner. 

The  "lenticular  glands"  present  same  characters  as  those  of 
stomach  of  Pig  No.  i. 

There  are  no  evidences  of  any  pathological  changes  in  the  in- 
terstitial connective  tissue. 

The  same  may  be  s^id  of  the  remaining  coats  of  this  organ. 

2.  Spleen.     (Section  G.  P.  539.) 


260 


CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


Plate  78 

Photomicrograph — Kidney  showing  malpighian  body  and    convoluted  tubules  of  guinea  pig   No.  2.     All 
cells   normal.     2  m.m.  objective  and  6X  compensating  eyepiece. 


Plate  79 


Photomicrograph  of  section  of  kidney  of^guinea  pig  No.  2,  showing  malpighian  bodies  and  convoluted  tubules. 
No  evidence  of  degenerative  changes.     Cells  normal.     16  m.m.  objective  and  6X  compensating  eyepiece. 


PRESERVATIVES.  261 

Alalpigliian  bodies  normal  in  size  and  number.  No  alterations 
in  the  walls  of  the  blood  vessels.  Capsule  and  trabeculae  show  no 
evidences  of  inflammatory  or  degenerative  changes. 

3.  Heart.     (Section  G.  P.  533.) . 
(i)     Endocardium  normal. 

(2)  Myocardium,  shows  no  changes  either  in  the  vessels, 
muscle  fibers  nor  the  interstitial  connective  tissues. 

(3)  Pericardium,  same  as  the  endocardium. 

4.  Kidneys.     (Section  G.  P.  537.) . 

These  organs  present  characters  similar  to  those  of  Pig  No.  i. 
The  Malpighian  bodies,  tubules,  interstitial  connective  tissues  and 
vessels  are  normal. 

5.  Suprarenals.      (Section  G.  P.  538.) 

Both  these  organs  are  normal,  presenting  no  evidences  of  dis- 
ease. 

6.  Pancreas.      (Section  G.  P.  540.) 

This  presents  no  character  differing  from  that  of  Pig  No  i, 
being  normal. 

Pig  No.  3.     Control. 

All  organs  of  this  animal  were  examined,  but  as  it  was  a  nor- 
mal, healthy  animal,  they  presented  no  characters  of  interest  in  this 
connection.  By  comparing  organs  from  this  animal  with  those  of 
No.  I  and  No.  2,  no  differences  could  be  seen,  either  in  structure  or 
staining  reactions. 

CONCLUSION. 

The  conclusion  to  be  drawn  from  these  sections,  after  careful 
comparisons,  would  be  that  all  three  animals  were  in  a  healthy  con- 
dition, and  that  whatever  diets  may  have  been  administered,  they 
had  no  effect  on  the  various  organs,  so  far  as  any  structural  altera- 
tions were  concerned.  I  could  not  detect  any  evidence,  either  of  a 
degenerative,  inflammatory,  necrotic  or  hyperplastic  process. 

W.  H.  Ingram. 

SERIES  NO.  II. 

The  second  series  of  experiments  to  determine  the  effect  of 
preservatives  on  animals  was  begun  on  May  14.  Three  guinea  pigs 
were  fed  5  milligrams  of  salicylic  acid  daily.  The  preservative  was 
mixed  with  a  well-known  breakfast  cereal.  Two  were  fed  with  5 
milligrams  of  benzoate  of  sodium  daily,  and  other  animals  were  fed 
the  same  food  as  these,  but  no  preservatives.     These  were  controls. 

There  were  three  females  in  the  series  and  we  did  not  know  in 
the  beginning  that  they  were  pregnant,  but  as  they  increased  in 
weight  so  rapidly,  it  became  apparent ;  therefore,  on  June  11  we  dis- 


262 


CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


I. 

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PRESERVATIVES.  263 

continued  taking  the  weights  of  these  three.  June  17-23  and  25 
were  celebrated  by  the  birth  of  the  young  ones.  On  July  we  again 
began  taking  the  weights  as  before.  This  we  continued  to  do  until 
July  18,  when  the  five  animals  were  submitted  for  pathological  and 
histological  analysis. 

CONDITIONS    NOTED  DURING   FEEDING. 

As  Stated  it  was  not  known  that  the  three  females  were  preg- 
nant at  the  beginning  of  this  experiment,  but  it  was  decided  after 
finding  out  the  fact,  that  it  was  just  as  well  to  go  through  the  ex- 


.^^K^^^mf^^^ 


Plate  80 

Photomicrograph  of  Kidney  of  guinea  pig  No.  4,  showing  malpighian  bodies  and  cell  arrangement.    There 
is  no  evidence  of  inflammatory  or  degenative  changes.     Magnified  150  diameters. 

periments  under  natural  conditions.  The  very  fact  that  the  three 
females  gave  birth  to  young  ones  within  the  term  is  interesting. 
The  young  pigs  were  immediately  given  adult  doses  of  preserva- 
tives as  soon  as  they  were  able  to  take  food  themselves,  and  the 
next  series  will  show  the  result.  During  the  term  there  was  no 
sign  of  sickness  on  the  part  of  these  animals;  all  seemed  active, 
particularlv  the  two  males.  These  were  quite  vicious.  One  day 
we  had  a  terrible  rain  storm  which  flooded  the  quarters  where  these 
animals  were  kept  and  fed,  and  rather  expected  that  they  might 
show  some  signs  of  sickness,  but  they  did  not.  This  would  seem 
to  indicate  that  the  preservatives  given  had  no  weakening  effect. 
The  report  of  Dr.  Ingram  here  appended  is  very  satisfactory. 


264  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

I  here  append  results  of  analysis  of  guinea  pigs  Nos.  i  to  5, 
Series  2,  sent  to  my  laboratory  for  pathological  examination. 

I.       POST-MORTBM    EXAMINATION. 

These  animals  were  all  killed  at  the  same  time,  and  "posted" 
while  still  warm,  in  manner  similar  to  those  of  Series  i. 

PIG  NO.    I. — MAI^K. 

(Fed  5  milligrams  salicylic  acid  daily  for  65  days.) 

(a)  Black,  shaggy  coat — a  very  vicious  animal  and  well  devel- 
oped. Subcutaneous  fat,  abundant.  Lymph  glands  of  inguinal, 
axillary  and  cervical  regions  not  enlarged ;  musculature,  normal. 

(b)  Abdominal  Cavity — No  gross  lesions  of  any  character  de- 
tected ;  all  organs  being  normal  in  size  and  position.  Contents  of 
viscera,  normal. 

(c)  Thoracic  Cavity — Lungs  distended,  normal  color;  heart 
and  vessels  show  no  changes ;  no  enlarged  lymph  glands. 

PIG  NO.  2. MALE. 

(Fed  5  milligrams  salicylic  acid  daily  for  65  days.) 
6         (a)   White,  black  hindquarters.     Very    large    pig.     Vicious 
and  well  developed.     Subcutaneous  fat,  normal ;  musculature,  nor- 
mal.    Axillary,  inguinal  and  cervical  glands,  normal. 

(b)  Abdominal  Cavity — Nothing  abnormal,  either  in  position 
or  size  detected.     Visceral  contents,  normal. 

(c)  Thoracic  Cavity — Nothing  abnormal  in  color,  position  or 
size  of  lungs,  heart  or  lymphoid  tissue. 

PIG  NO.  3. — FEMALE. 
(Fed  5  milligrams  salicylic  acid  daily  for  65  days.) 

(a)  White,  brown  hind  quarters,  nose  black,  weW  developed, 
soft  coat.  Subcutaneous  fat  normal.  Musculature,  same.  No  en- 
largement of  lymph  glands,  of  axillary,  inguinal  or  cervical  regions. 

(b)  Abdominal  Cavity — No  pathological  changes  in  size, 
shape  or  position  of  organs.  Not  pregnant.  Uterus  and  ovaries 
normal.  No  enlargement  of  lymphatic  structures.  Contents  of 
viscera  normal. 

(3)  Thoracic  Cavity — Nothing  abnormal  of  any  character  de- 
tected. 

PIG   NO.    4. 
(Fed  5  milligrams  benzoate  sodium  daily  for  65  days.) 
(a).    Brown  and  red  forequarters  and  face;  white  hindquar- 
ters.    Well  developed,  smooth  coat.     Subcutaneous  fat  abundant. 
Musculature,  normal.    No  enlargement  of  lymph  glands  in  any  part. 


PRESERVATIVES. 


265 


(b)  Abdominal  Cavity — No  changes  of  any  character  detected. 
Uterus  contains  four  embryo  pigs,  1.5  c.  m.  long.  These  are  nor- 
mal. 

(c)  Thoracic  Cavity — Nothing  abnormal. 

PIG  NO.  5. — :pemai.E. 

(Fed  5  milligrams  benzoate  of  sodium  daily  for  65  days.)  . 

(a)  Dark  brown,  white  face,  right  cheek  black;  left  red.  Well 
developed  animal.  Subcutaneous  fat  abundant.  Musculature  nor- 
mal.    No  enlargement  of  lymphoid  glands. 


Plate  81 

Photomicrograph  Kidney,  snowing  malpighian    body   and  convoluted  tubule  of  guinea  pig  No.  1.     Bow- 
man's capsule  and  the  beginning  of  the  urinary  tubule  or  canal.    All  cells  are  normal.    Magnified.500  diameters. 

(b)  Abdominal  Cavity — Nothing  abnormal  detected  in  size, 
shape  or  position.     Visceral  contents  normal. 

(c)  Thoracic  Cavity — No  pathological  changes  detected. 


MICROSCOPIC  EXAMINATION. 
PIG  NO.    I. — SERIES  NO.   2. 


1.  Heart — No.  554  normal  in  all  parts,  myocardium,  peri- 
cardium and  endocardium. 

2.  Pancreas — No.  555  normal,  no  changes  in  bodies  of  lan- 
gerhaus. 


266 


CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


Plate  82 

Photomicrograph  of  sections  of  kidney  of  guinea  pig  No.  5.  No  degenerative  changes  either  in  the  capsule 
tOjBowman  nor  in  the  glomerulus,  The  ascending  and  descending  limbs  of  Henle's  loop  are  normal.  The  in- 
ferstitial  connective  tissue  cells  are  stained  with  distinct  differentiation.     Magnified  150  diameters. 


Plate  83 


Photomicrograph  of  Suprarenal  and  adjoining  adipose  tissue  showing  capsule,  cortex  and  part  of  medulla. 
The  cells  are  normal.  No  pathological  changes.  From  a  section  of  guinea  pig  No.  4  which  was  fed  5  milligrams 
of  benzoate  of  sodium  daily  for  two  months.     Magnified  100  diameters. 


PRESERVATIVES. 


267 


3- 

4- 

5. 
6. 

7. 


Kidneys — No.  556  normal.     No  pathological  changes. 
Testicle — No.  559,  normal.     Spermatogenesis  very  active. 
Suprarenals — No.  556,  normal. 
Liver — No.  558,  normal. 


Stomach — No.  557,  normal. 
of  mucosa  or  in  any  parts. 

8.  Spleen — No.    556   normal, 
proliferation  or  degeneration. 

9.  Lnng — No.  553,  normal. 


No  changes  in  either  glands 
Malipghian  bodies   show   no 


PIG  NO.  2. — SERIES  NO.  2. 

Heart — No.  574,  normal. 

Lungs — No.  573,  normal. 

Stomach — No.  578,  normal. 

Pancreas — No.  759,  normal. 

Liver — No.  583,  normal. 

Liver  and  gall — bladder — No.  582,  normal. 

Kidneys — No.  581,  normal. 

Suprarenals — No.  581,  normal. 

Spleen — No.  580,  normal. 


Plate  84 

r  -*«  Gall  bladder  photomicrograph,  showing  the  wall  which  is  composed  of  the  mucus,  fibro  muscular,  subser- 
ous and  serous  coats.  There  are  no  degenerative  changes  shown  in  the  cells  of  the  wall.  The  glands  in  the 
tunica  propria  of  the  mucosa  are  normal.  From  guinea  pig  No.  1,  series  II,  which  was  fed  5  milligrams  of  sali- 
cylic acid  daily  for  two  months.     Magnified  100  diameters. 


PIG  NO.  3. — SERIES  NO.  2. 

1.  Heart — No.  562,  normal. 

2.  Lungs — No.  563,  normal. 

3.  Liver — No.  565,  normal. 

4.  Oesophagus — No.   564,  normal. 

5.  Stomach — No.   568,  normal. 


268  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

6.  Kidney — No.  567,  normal. 

7.  Suprarenals — No.  567,  normal. 

8.  Liver — No.  566,  normal. 

9.  Spleen — No.  569,  normal. 
10.  Intestine — No.  571,  normal. 


I 
2 
3 
4 
5 
6 

7 
8 

9 

10, 


PIG  NO.  4. — SERIES  NO.    2. 

Heart — No.  584,  normal, 
lyungs — No.  583,  normal. 
Liver — No.  587,  normal. 
Spleen — No.  590,  normal. 
Pancreas — No.  588,  normal. 
Stomach — No.  589,  normal. 
Kidneys — No.  586,  normal. 
Suprarenals — No.  587,  normal. 
Placenta  and  uterus — No.  592,  normal. 
Foetus — No.  593,  normal. 


Plate  85 

Photomicrograph  showing  glands  of  the  mucous  membrane  of  the  stomach,  cardiac  end.  There  .is  no  evi- 
dence of  degenerative  changes.  Guinea  pig  No.  1.  The  cells  are  all  beautifully  arranged,  and  ,  show  no 
neicrotic  processes  nor  injury  from  the  daily  dose  of  preservatives.     Magnified  750  diameters. 

PIG  NO.  5 — SERIES  NO.  2. 

1.  Heart — No,  542,  normal. 

2.  Lungs — No.  543,  normal. 

3.  Liver — No.  544,  normal. 

4.  Spleen — No.  546,  normal. 

5.  Pancreas — No.  547,  normal. 

6.  Stomach — No.  548,  normal. 

7.  Uterus — No.  549,  normal. 

8.  Fallopian  tubes — No.  549,  normal. 


PRESERVATIVES. 


Plate  86 

"—-^^Photomicrograph  of  the  lung  of  guinea  pig  No.  1,  showing  bronchus  with  convoluted  mucosa.  The  clear 
spaces  are  air  passages  and  infundi  bula.  The  notches  in  the  walls  of  the  clear  spaces  are  the  air  vesicles 
Conditions  normal.     Magnified  50  diameters. 


%    % 


Plate  87 


Photomicrograph  showing  glands  of  the  mucous  membrane  of  the  stomach,  cardiac  end.  The  cells  are 
normal  in  size,  and  there  is  no  evidence  of  inflammation  or  degenerative  changes.  Section  made  from  stomach 
of  guinea  pig  No.  5,  which  was  fed  on  5  milligrams  of  benzoate  of  sodium  daily  for  two  months.  Magnified  500 
diameters. 


270  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

9.     Kidneys — No.  551,  normal. 
10.     Suprarenals — No.   551,  normal. 
The  same  technique  was  employed  as  in  Series  i. 

SERIES  NO.  3. 

The  third  series  of  experiments  was  conducted  with  animals 
which  were  fed  on  preservatives  from  the  time  they  were  able  to 
take  food  themselves — from  babyhood  up  to  maturity.  Two  of 
these  were  fed  5  milligrams  of  salicylic  acid  daily,  and  two  were 
fed  5  milligrams  of  benzoate  of  sodium  daily.  During  the  whole 
course  of  feeding,  they  showed  no  signs  of  sickness,  but  on  the 
contrary,  seemed  more  active  and  healthy  than  the  controls,  born 
about  the  same  time. 


Plate  88 

Photomicrograph  of  the  intestine  of  guinea  pig  No.  2,  showing  the  crescentic  valve-like  folds  of  the  mucosa 
and  the  villi,  also  the  tubular  glands  called  follicles  or  crypts  of  Lieberkuhn.  Running  along  the  base  is  the 
muscularis  mucosae.     Conditions  normal.     Magnified  50  diameters. 

Considering  the  age  and  size  of  these  guinea  pigs,  and  the 
amount  of  the  preservatives  fed  to  them,  we  regard  this  as  a  crucial 
test,  and  from  a  therapeutical  standpoint,  might  be  sufficient  evi- 
dence that  these  preservatives  are  harmless.  Three  of  these  animals 
were  born  on  July  15,  their  mother  being  the  fourth  animal  in 
Series  No.  2.  The  other  one  was  born  on  July  23,  its  mother  be- 
ing the  third  animal  in  Series  No.  2.  Just  one  week  after  these 
baby  pigs  were  born,  they  were  put  on  the  preservative  diet,  in  the 
same  proportions  as  were  administered  to  the  full  grown  animals 
in  the  other  series. 

On  September  i  we  took  them  to  the  laboratory  for  pathologi- 
cal and  histological  analysis. 

A  study  of  the  table  will  show  that  all  of  these  little  pigs  gained 
steadily  in  weight,  if  anything  they  gained  more  in  proportion  than 
the  other  young  ones  born  about  the  same  time,  and  which  were  not 
fed  on  any  preservatives.     The  following  is  Dr.  Ingram's  report : 


PRESERVATIVES. 


271 


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272 


CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


I  here  append  reports  of  examination  of  guinea  pigs  Nos.  i  to 
4,  Series  3.     These  four  pigs  were  heahhy  and  very  active. 

The  animals  were  killed  at  the  same  time,  and  in  similar  m.an- 
ners  as  Series  No.  i  and  No.  2. 

(l)    POST-MORTEM    APPEARANCES. 
GUINEA  PIG  NO.   I,  SERIES  3. 

(a)  Male,  black  face,  white  forequarters,  red  hindquarters. 
Subcutaneous  fat,  normal.  No  enlargement  of  the  lymph  glands. 
Musculature  normal. 

(b)  Thoracic  cavity — No  lesions  appreciable  of  any  of  the 
organs. 

(c)  Abdominal  cavity ^-All  organs  normal  in  position  and 
size. 


Plate  cSy 

Photomicrograph  showing  glands  of  the  mucous  membrane  of  the  stomach  of  guinea  pig  No.  1.  Cardiac 
end  cells  are  normal  in  size  and  there  is  no  evidence  of  inflammation  or  degenerative  changes.  Magnified  500 
diameters. 

GUINEA  PIG  NO.   2,  SERIES  3. 

(a)  Male,  right  side  of  the  face  brown,  left  side  red,  body  red, 
right  foot  front  white.  Subcutaneous  fat  normal.  No  glandular 
enlargement.     Musculature  normal. 

(b)  Thoracic  cavity — No  change  in  position,  size,  etc.,  of  the 
organs  of  this  cavity. 

(c)  Abdominal  cavity — Organs  normal  in  size  and  position. 


PRESERVATIVES.  273 

CxUTNEA    PIG   NO.    3.    SKRIKS    3. 

(a)  Male.  Right  forequarters  and  face  red.  Left  forequar- 
ters  and  face  brown.  Both  hindquarters  white.  White  stripe  in  the 
median  hne  of  the  face.  Subcutaneous  fat  and  musculature  normal. 
No  glandular  enlargements. 

(b)  Thoracic  cavity— Contents  normal  in  size,  etc. 

(c)  Abdominal  cavity — Organs  normal  in  position,  size  and 
contents. 


Plate  90 

Photomicrograph  of  a  section  of  Guinea  Pig  No.  2.  No  degenerative  changes  either  in  the  capsule  o 
Bowman  or  in  the  glomerulus.  The  ascending  and  descending  limbs  Heule's  loops  are  normal  in  size  and 
appearance.  The  collecting  tubules  are  normal.  The  interstitial  connective  tissue  cells  are  stained  with  distinct 
differentiation.     Magnified  100  diameters. 

GUINEA  PIG  NO.  4,  SERIES  3. 

(a)  Male.  Right  side  of  face  black,  left  white,  right  fore- 
quarters  black,  left  white;  left  hindquarters  black,  right  hindquarters 
white  and  black.  Subcutaneous  fat  and  musculature  normal.  No 
enlargement  of  the  lymph  glands. 

(b)  Thoracic  cavity — Nothing  abnormal  in  position  and  other 
indications. 

(c)  Abdominal  cavity — Normal  in  contents. 
(2)     Microscopic  examination. 

(i)  Guinea  Pig  No.  i.  Series  3.  (Fed  on  5  milligrams  sal- 
icylic acid  daily). 

(i)     Lungs — Guinea  pig,  section  No.  598,  normal. 


274 


CANNING  AND  PRESERVING  OP  FOOD  PRODUCTS. 


Plate  91 

Photomicrograph  of  the  Pancreas  of  guinea  pig  No.   2. 
in  size  and  form.     Magnified  200  diameters. 


The  bodies  of  Langerhaus  and  gland  cells  are 


Plate  92 

Photomicrograph  of  the  small  intestine  of  guinea  pig  No.  3,  showing  the  villi  glands  of  Lieberkuhn, 
Lymph  nodules,  Muscularis  mucosae,  Submucosa  and  Muscularis.  No  changes.  Normal.  Magnified  100 
diameters. 


PRESERVATIVES. 


275 


(2)  Heart — Guinea  pig,  section  No.  599,  normal. 

(3)  Spleen — Guinea  pig,  section  No.  600,  normal. 

(4)  Pancreas — Guinea  pig,  section  No.  601,  normal. 

(5)  Stomach — Guinea  pig,  section  No.  602,  normal, 
tents,  partly  digested  food. 

(6)  Liver  and   gall  bladder — Guinea  pig,   section  No. 
normal  (both). 

(7)  Kidneys  and  suprarenals — Guinea  pig,  section  No.  604, 
normal    (both). 

(8)  Small  intestine — Guinea  pig,  section  No.  605,  normal 
(2)     Guinea  pig  No.  2,  Series  3.      (Fed  on  5  milligrams  of 

sodium  benzoate  daily.) 


Con- 


603, 


Plate  IJo 

Photomicrograph  showing  glands  of  the  mucous  membrane  of  the  stomach.     Normal.     Frcm  guinea  pig  No 
4.      Magnified  100  diameters. 


(i)     Lungs — Guinea  pig,  section  No.  606,  normal. 

(2)  Heart — Guinea  pig,  section  No.  607,  normal. 

(3)  Spleen — Guinea  pig,  section  No.  608,  normal. 

(4)  Pancreas — Guinea  pig,  section  No.  609,  normal. 

(5)  Stomach — Guinea  pig,  section  No.  610,  normal.     Con- 
tents same  as  No.  602. 

(6)  Liver  and  gall  bladder — Guinea  pig,  section  No.   611, 
normal  (both). 

(7)  Liver   (second  section) — Guinea  pig,  section  No.  612, 
normal. 


276  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

(8)  Kidneys  and  suprarenals — Guinea  pig,  section  No.  613, 
normal  (both). 

(3)  Guinea  pig  Xo.  3,  Series  3  (Fed  on  5  milligrams  ot  sal- 
icylic acid  daily). 

(i)     Heart — Guinea  pig,  section  No.  614,  normal. 

(2)  Lungs — Guinea  pig,  section  No.  615,  normal. 

(3)  Spleen — Guinea  pig,  section  No.  616,  normal. 

(4)  Pancreas — Guinea  pig,  section  No.  617,  normal. 

(5)  Stomach — Guinea  pig,  section  No.  618,  normal.  Con- 
tents same  as  No.  602. 

(6)  Kidneys  and  Suprarenals — Guinea  pig,  section  No.  619, 
both  normal. 


Plate  94 

^Photomicrograph  of  kidney,  showing  malpighian  body  and  convoluted  tubule  of  guinea  pig  No.  3.     Bow- 
man's'capsule  and  the  beginning  of  the  urinary  tubule  or  canal.     All  cells  are  normal.    Magnified  450  diameters. 

(7)  Liver  and  Gall  Bladder — Guinea  pig,  section  No.  620, 
both  normal. 

(4)  Guinea  pig.  No.  4,  Series  3.  (Fed  on  5  milligrams  of 
sodium  benzoate  daily.) 

(i)      Heart — Guinea  pig,  section  No.  621,  normal. 

(2)  Lungs — Guinea  pig,  section  No.  622,  normal. 

(3)  Spleen — Guinea  pig,  section  No.  623,  normal. 

(4)  Pancreas — Guinea  pig,  section  No.  624,  normal. 

(5)  Stomach — Guinea  pig,  section  No.  625,  normal.  (Con- 
tents same  as  No.  602.) 

(6)  Kidneys  and  Suprarenals — Guinea  pig,  section  No.  626, 
both  normal. 

(7)  Liver  and  Gall  Bladder — Guinea  pig,  section  No.  627, 
both  normal. 


PRESERVATIVES.  277 

CONCLUSION. 

The  technique  being  the  same  in  these  three  series,  a  uniform 
result  was  thus  obtained.  From  these  analyses  of  this  series,  the 
same  conclusion  must  be  arrived  at  as  in  the  series  No.  (i)  and  (2), 
that  is,  that  the  conditions  these  guinea  pigs  were  subject  to,  had 
no  effect,  so  far  as  producing  lesions  of  any  organs,  appreciable  by 
pathological  methods. 

W.  H.  Ingram. 


SERIE:S   (4).       RHSUIvT  FROM  F'EEDING  RABBITS  ON  PRESERVATIVES. 

It  has  been  stated  by  famous  pharmacologists,  that  it  is  good 
therapeutics  to  base  an  opinion  as  to  the  effects  of  a  drug  on  the  re- 
sults obtained  by  feeding  in  stated  quantities  to  animals.  If  there 
were  no  physiological  ill  effects  noticed  and  if  the  internal  organs 
showed  no  hyperplastic,  pathological  or  degenerative  changes,  it 
was  a  fair  assumption  that  the  drug  would  have  no  harmful  or  in- 
jurious effect  upon  the  human  organism.  This  is  indeed  the  meth- 
od employed  to  determine  the  character  of  all  known  substances, 
particularly  at  the  time  they  are  first  discovered. 

We  have  completed  the  fourth  series  of  such  experiment  with 
salicylic  and  benzoic  acids  and  this  series  has  some  interesting  fea- 
tures. On  May  14  we  received  several  very  young  rabbits  along 
with  our  guinea  pigs,  and  selected  two  for  experimental  purposes. 
These  appeared  in  the  photograph  published  in  the  May  issue  of 
the  ''Index"  and  are  reprinted  here. 

The  young  rabbits  which  we  intended  for  controls  did  not  get 
along  well  and  soon  died,  but  the  two  kept  for  the  experiment  grew 
rapidly  and  were  never  sick  a  single  day  during  the  whole  term  of 
feeding.  They  were  always  active  and  playful  and  we  became  so 
much  attached  to  them  that  we  disliked  to  kill  them  for  the  patho- 
logical analysis.  During  the  months  of  August  and  September  we 
gave  the  5  milligrams  of  benzoate  of  sodium  daily,  in  addition  to 
their  daily  dose  of  5  milligrams  of  salicylic  acid.  They  seemed  to 
relish  their  food  very  much  and  would  always  come  running  to  us 
every  time  we  approached  their  cage.  They  were  always  hungry 
and  I  believe  we  might  have  given  them  double  the  quantity  of  pre- 
servatives without  injuring  them  in  the  least.  During  the  term 
of  feeding  they  never  seemed  drowsy  and  I  often  wondered  when 
they  obtained  enough  sleep,  for  on  moonlight  nights  I  could  see 
them  running  around  very  lively. 

On  May  14  the  white  bunny  weighed  11^  ounces  and  the 
grey  weighed  7J4  ounces — they  were  mere  babies.  From  that 
date     upto  August  i  we  fed  them  5  milligrams  of  salicylic  acid 


278  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS- 

daily  and  they  weighed  at  tliat  time  35  and  34  ounces  respectively. 
After  that  we  administered  the  two  preservatives  as  previously  men- 
tioned and  at  the  end  of  the  term  they  weighed  49VS  and  43  ounces 
respectively.  They  were  then  killed  for  pathological  and  histological 
analyses  by  Doctor  R.  G.  Burns,  a  noted  pathologist,  and  the  bac- 
teriologist for  the  city  of  Alleghen}-,  Pa.  The  following  is  his  re- 
port : 

DOCTOR  burns'   REPORT. 

, ,  Nov.  15,  1904. 

I  herewith  submit  reports  of  examination  of  rabbits: 
These  two  rabbits  were  very  active  and  healthy. 
The  rabbits  were  killed  at  the  same  time  and  in  similar  manner 
by  chloroform.     The  technique  was  as   follows.     The  organs  of 


Plate  95 

Photomicrograph  showing  glands  of  the  gastric  mucous  membrane.  There 
is  no  evidence  of  degenerative  changes.  The  ceils,  with  their  nuclei,  are  beauti- 
fully stained  with  Haematoxylin  and  Eosine.  The  Parietal,  smooth  muscle,  and 
chief   cells   are   plainly   visible.     Magnified   500   diameters.     Rabbit  No.   1. 

these  animals  were  placed  in  a  4  per  cent  solution  of  formalde- 
hyde, the  several  organs  were  cut  into  slices  two  millimeters  thick. 
After  remaining  in  this  fixing  solution  for  36  hours  they  were  placed 
in  running  water  for  24  hours  and  then  in  60  per  cent  alcohol,  then 
80,  and  finally  in  absolute  alcohol. 

From  the  alcohol  they  were  placed  in  equal  parts  of  absolute 
alcohol  and  ether  for  36  hours. 

The  embedding  was  in  celloidin,  two  solutions,  one  thin,  in 
which  they  remained  for  48  hours,  the  otlicr  thick.   They  were  next 


PRESERVATIVES. 


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CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


placed  upon  wood  blocks  and  cut  with  Stucket's  microtome.  Stained 
with  Haemoloxyln  and  Eosin,  mounted  in  Canada  balsam ;  sections 
stained  easily. 


POST-MOETEM  APPEARANCES. 


RABBIT  NO.  I 


(a)  Grey  color,  no  enlargement  of  lymph  glands,  muscular 
and  subcutaneous  fat  normal. 

(b)  Thoracic  cavity — Organs  normal  as  to  position  and  size. 

(c)  Abdominal  cavity — Organs  normal  as   to    position    and 
size,  stomach  contents  partially  digested. 


Plate  96 

Photomicrograph  section  of  kidney  of  Rabbit  No.  1,  which  had  been  fed  on  pre- 
servatives for  five  months.  The  malpighan  bodies  are  normal  in  size,  number 
and  position.  The  tubules  of  both  organs  are  normal.  There  are  no  degenerative 
changes.      The  cells  are  stained  clearly.    Magnified  250  diameters. 


MICROSCOPIC   EXAMINATION. 


RABBIT  NO.    I. 


Lungs  normal. 
Heart  normal. 
Spleen  normal. 
Pancreas  normal. 
Stomach  normal. 
Liver  normal. 
Kidneys  normal. 
Small  intestines  normal. 


PRESERVATIVES.  281 

POST-MORTEM. 
RABBIT    NO.    2. WHITE    COI.OR. 

Organs  of  thoracic  and  abdominal  cavities  normal  as  to  posi- 
tion and  size.  Lymph  glands,  muscular  and  subcutaneous  fat  nor- 
mal, stomach  contents  partially  digested. 

MICROSCOPIC  EXAMINATION. 
RABBIT  NO.   2. 

1.  Lungs  normal. 

2.  Heart  normal. 

3.  Spleen  normal. 


Plate  97 

Photomicrograph  of  gastric  mucous  jnembrane  of  Rabbit  No.  2,  -which  had 
been  fed  on  preservatives  for  five  months.  There  is  no  evidence  of  necrotic 
hyperplastic,  degenerative  of  inflammatory  changes.  The  glands  and  cells  are  nor- 
mal.    Magnified   200   diameters. 

4.  Pancreas  normal. 

5.  Stomach  normal. 

6.  Liver  normal. 

7.  Kidneys  normal. 

8.  Small  intestines  normal. 

Microscopic  slides  of  which  are  herewith  submitted. 

Very  truly, 
R.  G.  Burns,  M.  D. 


282  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

Dr.  Burns  was  not  present  at  any  time  during  the  feeding  term 
of  these  animals  and  was  not  famihar  with  the  preservative  experi- 
ment and  did  not  know  on  what  diets  the  animals  had  been  fed, 
therefore  his  analyses  are  entirely  independent  of  the  feeding, 
and  he  was  not  influenced  by  any  knmvledge  of  the  facts  and  his 
results  as  are  reported  just  as  he  found  them. 

We  examined  the  slides  carefully  under  various  magnifying 
powers  and  here  append  our  findings. 

Slide  of  the  stomach  of  white  rabbit. — The  stomach  wall  in- 
cluding the  mucosa,  submucosa,  muscularis,  and  serosa,  appeared 


Plate  98 

Photomicrograph  of  a  Malpighan  body  of  the  kidney  of  Rabbit  No.  2.  The 
convoluted  tubules,  Bowman's  capsule,  Glomerulus,  are  all  normal.  The  cells, 
with  their  nuclei,  are  well  stained  with  Haematoxylin  and  eosine.  No  degenerative 
changes.      Magnified  500   diameters. 

perfect  in  every  respect;  there  were  no  lesions  or  anything  that 
would  indicate  injury.  The  fundus  glands  were  stained  perfectly, 
showing  the  parietal  cells  with  nuclei  clearly  stained;  the  smooth 
muscle  cells  and  the  chief  cells  seemed  to  be  properly  arranged. 
The  pyloric  glands  were  normal  in  size  and  position ;  the  epithelium 
of  the  surface,  the  tunica  propria,  solitary  follicles  were  all  normal. 
The  slide  of  the  gray  rabbit's  stomach  presented  no  different  ap- 
pearance. 

Slide  of  the  kidneys  from  the  white  rabbit. — These  sections  suf- 
fered somewhat  in  mounting.  The  glomeruli  were  somewhat  dis- 
arranged, but  there  were  no  disease  processes.   The  convoluted  tub- 


PRESERVATIVES.  283 

ules  and  their  cells  were  all  normal,  likewise  Bowman's  capsules. 
The  cells  in  the  glomeruli  were  all  distinctly  stained  with  the  nuclei 
standing  out  prominenth'.  The  blood  vessels  and  urinary  tubules 
were  normal  in  appearance.  The  ascending  and  descending  arms 
of  Henle's  loops  are  plainly  visible,  and  are  normal  in  appearance. 
The  convoluted  tubules  of  the  first  order  are  normal  in  size,  number 
and  position.  The  general  appearance  of  the  kidney  consisting  of 
the  tunica  albuginea,  medullary  rays,  convoluted  tubules  both  of  the 
first  and  second  order,  cortex,  medulla,  veins  and  arteries  was  that 
of  a  healthy  animal  and  showed  no  evidence  of  degenerative  pro- 
cesses. 

The  slide  from  the  gray  rabbit  had  no  dififerent  appearance  so 
far  as  we  were  able  to  determine. 

Since  these  two  organs,  viz.,  the  stomach  and  the  kidneys,  are 
the  ones  most  likely  to  show  the  effects  of  any  improper  diets,  we 
have  not  made  any  more  extended  microscopical  examination  of 
the  other  organs  and  simply  refer  the  reader  to  Dr.  Burns'  report. 

The  results  obtained  by  the  pathological  analyses  of  the  four 
series  of  animals  are  most  gratifying.  We  are  inclined  to  believe 
that  all  the  professional  opinions  expressed  as  to  the  harmful  effects 
of  salicylic  and  benzoic  acids  in  the  amounts  ordinarily  employed 
as  preservatives  in  food  products  are  unwarranted  by  the  facts.  We 
certainly  do  not  believe  them  and  from  what  we  have  observed  in 
these  experiments  we  are  inclined  to  take  the  other  side.  We  have 
not  been  prejudiced,  we  have  been  seeking  to  learn  tlie  truth,  and 
we  have  learned  that  some  of  the  most  respected  professional  men 
in  this  country  have  been  expressing  opinions  concerning  preserva- 
tives without  making  personal  investigation.  This  is  lamentable, 
because  it  casts  a  shadow  on  the  integrity  of  the  men  who  stand  out 
so  boldly  as  opponents  of  preservatives.  Take  for  instance  the 
statement  by  a  well  known  champion  of  the  opposition,  ''that  be- 
cause preservatives  are  anti-ferments  and  therefore  stop  processes 
of  decay,  in  just  that  proportion  will  they  interfere  with  the  fer- 
ments of  digestion."  Nothing  could  be  farther  from  the  truth,  yet 
this  same  error  and  misconception  is  embodied  in  the  very 
first  resolution  offered  to  the  International  Pure  Food  Congress  by 
the  committee  on  preservatives.  It  reads:  "Whereas,  etc.,  be  it 
resolved  (i).  That  this  congress  does  not  approve  of  the  use  of 
preservatives  or  antiseptics  other  than  those  above  named  (salt, 
sugar,  vinegar  and  wood-smoke),  which,  to  be  effective,  must  de- 
stroy or  paralyze  all  fermentative  organisms.  They  induce  a  con- 
dition which  must  be  more  or  less  unfavorable  to  digestion  and  they 
are  therefore  to  this  extent  hurtful."  This  resolution  is  signed  by 
the  following  persons  :  H.  W.  Wiley,  J.  H.  Shepard,  V.  L.  Price,  E. 
F.  Ladd.  Julius  Hortyett,  William  Berkely  and  Richard  Fischer. 


284  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

There  is  not  a  single  particle  of  truth  in  this  resohition.  Every  one 
of  the  substances  mentioned  as  being  non-injurious  have  fully  as 
much  harmful  effect  on  digestion  as  the  well  known  preservatives, 
salicylic  and  benzoic  acids,  weight  for  weight.  Some  of  them  will 
retard  digestion  more  than  these,  vinegar  and  creosote  from  smoke, 
for  example.  Hydrochloric  acid,  one  of  the  most  powerful  anti- 
ferments  known,  is  absolutely  essential  to  digestion — digestion  by 
pepsin  cannot  proceed  w^ithout  hydrochloric  acid ;  how  then  can  the 
resolution  be  true?  Some  of  these  men.  as  learned  as  they  are  in 
some  directions,  do  not  seem  to  know  that  fermentation  accom- 
plished by  bacteria,  yeasts  and  molds  is  as  much  different  from  the 
digestive  processes  as  ignorance  is  from  knowdedge.  Just  follow 
out  such  reasoning — if  all  anti-ferments  exert  an  injurious  effect 
on  the  digestive  processes,  how  in  the  w^orld  are  w^e  going  to  elimin- 
ate the  0.2  per  cent  of  hydrochloric  acid  which  is  poured  into  the 
stomach  by  the  glands  of  the  gastric  mucous  membrane?  Because 
cranberries  contain  benzoic  acid,  shall  we  refrain  from  eating  that 
delightful  sauce  with  our  turkey  dinners,  simply  because  a  few  radi- 
cals declare  that  it  interferes  with  digestion?  Any  sensible  and 
thinking  person  knows  better  than  that ;  every  one  knows  that  cran- 
berry sauce  assists  digestion,  and  this  sauce,  as  it  is  prepared  for  the 
table,  contains  benzoic  acid  in  the  proportion  of  i  to  2,000  and  more. 
Reverse  the  reasoning :  arsenic  is  a  dangerous  and  deadly  poison  to 
man ;  it  will  absolutely  stop  all  digestive  processes  in  small  doses,  but 
poisonous  as  it  is  to  mankind,  it  has  very  little  effect  on  bacteria,  and 
in  the  same  proportion  does  not  interfere  at  all  w^ith  the  putrefactive 
bacteria.  The  statisticians  inform  us  that  the  average  length  of  life 
has  increased  PIVB  YEARS  zuithin  the  last  decade.  To  what 
cause  can  this  felicitous  improvement  be  traced?  Some  have  at- 
tempted to  answer  this  question  by  stating  that  the  science  of  medi- 
cine has  made  wonderful  strides  and  new  remedies  have  been  dis- 
covered. vSome  say  that  there  are  better  sanitary  conditions,  and 
there  are  better  methods  of  combating  diseases  by  quarantine  laws 
and  regulations.  Some  say  that  we  have  better  food  since^  the 
jTerm  theory  has  become  better  understood.  Let  us  ask  ourselves  a 
few  questions. 

What  is  the  most  frequent  cause  of  death?  Bacteria  of  dis- 
eases ? 

What  is  the  effect  of  newly  discovered  remedies  ?  Do  they  de- 
stroy bacteria  ? 

Has  the  medical  science  advanced  in  proportion  to  the  discov- 
ery of  the  bacteria  which  cause  diseases,  and  the  antiseptics  used  to 
combat  them? 

Has  the  increased  amount  of  chemically  preserved  food  any- 
thing to  do  with  the  lessening  of  diseases?     Why  have  they  not 


PRESERVATIVES.  285 

shortened  life  as  the  opponents  of  food  preservatives  claim?  Is  it 
possible  that  preservatives  might  be  the  means  of  preventing  the 
multiplication  of  disease  bacteria  in  food  ? 

Is  it  not  possible  that  the  increased  longevity  may  be  due  di- 
rectly to  the  increased  consumption  of  chemically  preserved  food  ? 

Bacteria  are  the  cause  of  most  deaths,  and  the  antiseptics  are 
the  means  we  have  at  hand  for  opposing  them.  Shall  we  not  be 
very  caref til  how  we  restrict  their  usefulness  ?  Is  it  not  a  possibility 
that  the  pure  food  experts  are  attempting  to  drive  out  of  our  mar- 
kets the  very  best  food  ever  prepared  for  the  health  and  happiness  of 
mankind?     We  merely  ask  the  questions. 


286  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

CHAPTER  IX. 

Chemical  Antiseiitics 

Benzoic  Acid. — Method  of  Detection. — Salicylic  Acid. — Method  of 
Detection.  Formaldehyde. — Method  of  Detection.  Boracic 
Acid. — ]\Iethod  of  Detection. — ]\liquels  Table  of  Antiseptics  and 
Their  Relative  Value. 


Only  a  few  chemicals  have  any  very  great  antiseptic  value  and 
the  number  which  is  used  commonly  in  preserving  food  is  limited  to 
three  or  four.  Of  course,  there  are  various  substances  which  have 
antiseptic  value,  such  as  sugar,  salt  and  vinegar,  but  we  have  ref- 
ference  only  to  chemicals  which  are  prepared  and  sold  to  the  trade 
for  preserving  purposes.  These  are  benzoic  acid,  more  commonly 
used  in  the  form  of  benzoate  of  sodium;  salicylic  acid,  boric  acid 
and  borax,  and  formaldehyde. 

Benzoic  acid  (CcHgCOs)  is  made  from  benzoin  by  sublima- 
tion. It  is  artificially  prepared  from  tuluol  and  may  be  obtained 
from  toluene  (CyHgC),  or  naphthalin  (CioHg)  from  hippuric  acid. 

The  English  benzoic  acid  is  prepared  from  certain  varieties  of 
Botany  Bay  gum  (gum  acroides),  and  is  superior  to  the  German 
product.  The  form  usually  employed  as  a  preservative  is  benzoate 
of  sodium  (NC7H5O2)  which  is  made  by  simply  neutralizing  ben- 
zoic acid  with  carbonate  of  soda. 

It  is  white  and  very  light,  with  odor  of  benzoin,  has  a  sweetish 
astringent  taste ;  it  is  soluble  in  twenty  parts  of  water  and  forty-five 
parts  of  alcohol.  It  is  used  as  a  medicine  for  gout,  rheumatism, 
lithaemia  and  lithaemic  gravel,  puerperal  fever  and  tuberculosis. 
As  a  preservative  it  is  powerful  in  the  proportion  of  i  to  909  (Mi- 
quel),  and  prevents  the  growth  of  molds,  yeasts  and  nearly  all  bac- 
teria. It  is  employed  largely  in  the  manufacture  of  catsups,  pulps, 
sauces,  fruit  butters,  jams,  preserves,  meats,  beer,  wines,  and  in  fact, 
practically  takes  the  place  of  salicylic  acid,  which  was  prohibited  by 
law  in  the  years  1893  and  1896  in  the  various  states.  The  laws  of 
many  states  do  not  permit  the  employment  of  this  or  any  other  anti- 
septic, but  there  is  a  disposition  to  be  lenient  with  the  manufactur- 
ers of  tomato  products  pending  the  reports  of  the  results  of  experi- 
ments now  being  made.  There  will  therefore  be  no  action  taken 
against  the  use  of  benzoate  of  sodium  in  catsup,  Chili-sauce,  etc..  at 
present,  unless  the  quantities  used  are  in  excess;  i-iooo  will  prob- 


CHEMICAL  ANTISEPTICS.  287 

ably  be  allowed  until  the  department  at  Washington  gets  more  in- 
formation on  the  effect  of  this  chemical  upon  the  human  body. 

Owing  to  the  fact  that  many  manufacturers  of  food  products 
purchase  part  of  their  preserved  material  w^hich  they  use  in  special 
formulae,  it  is  w^ell  for  them  to  be  acquainted  with  official  tests  em- 
ployed to  ascertain  wdiat  preservatives,  if  any,  have  been  used.  The 
manufacturer  will  be  enabled  to  make  these  tests  for  himself  if  he 
observes  closely  each  step  in  the  analysis. 

DETECTION  OF  BENZOIC  ACID. 

Make  a  chloroform  extract  of  the  material  to  be  examined.  If 
liquid,  make  slightly  alkaline  with  sodium  hydroxid,  and  first  strain 
through  flannel,  then  acidify  with  33^^  per  cent  sulphuric  acid,  and 
add  about  10  per  cent  of  the  bulk  of  chloroform  or  ether. 

If  the  material  is  of  solid  nature,  dissolve  by  maceration  with 
water,  a  little  more  than  equal  weight,  and  proceed  as  with  liquid. 

After  making  chloroform  extraction  separate  this  from  water 
by  means  of  a  separatory  funnel.  If  the  extract  be  clear,  evaporate 
at  a  low  temperature  until  a  residue  is  formed.  In  the  event  of  the 
solution  not  being  clear,  the  result  may  be  obtained  by  using  the 
centrifugal  machine  (Fig.  XI).  Take  up  residue  with  a  small 
quantity  of  hot  water  and  make  the  following  three  tests  for  ben- 
zoic acid : 

First.  Sublimation  method  (Teach).  Evaporate  an  ammon- 
iacal  solution  of  the  ether  extract  to  dryness  in  a  large  watch-glass 
by  the  aid  of  a  gentle  heat.  Fasten  with  clips  or  otherwise  a  sec- 
ond watch-glass  to  the  first,  edge  to  edge,  so  as  to  form  a  double 
convex  chamber  with  a  cut  filter  paper  between.  Place  upon  a 
small  sand-bath  and  heat.  Benzoic  acid,  if  present,  will  sublime  upon 
the  surface  of  the  upper  glass  in  minute  needles,  recognizable  under 
the  microscope.  It  may  further  be  tested  by  determining  the  melt- 
ing-point of  the  crystals,  or  by  treating  the  residue  with  ammonia, 
and  after  evaporation  and  solution  of  the  residue,  applying  the  ferric 
chlorid  test. 

Second  Method.  — Make  a  part  of  the  extract  distinctly  alka- 
line with  ammonium  hydroxid ;  expel  excess  of  ammonia  by  evapor- 
ation, take  up  the  residue  with  small  quantity  of  water  and  add  a 
few  drops  of  a  neutral  0.5  per  cent  solution  of  ferric  chlorid.  The 
reaction  will  be  a  brown-colored  precipitate  of  benzoate  of  iron,  if 
benzoic  acid  be  present. 

Third  Method. — Evaporate  a  portion  of  the  original  extract 
and  add  a  small  quantity  of  chemically  pure  sulphuric  acid,  then 
heat  until  white  fumes  are  given  off.  All  the  organic  matter  is 
charred  and  the  benzoic  acid  is  converted  into  sulplio-benzoic  ^cid. 


288  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

To  this  add  a  few  crystals  of  potassium  nitrate,  and  there  is  formed 
meta-di-nitro-benzoic  acid. 

This  acid  should  be  cooled  and  diluted  with  water,  then  add 
ammonia  in  excess,  and  then  add  a  drop  or  two  of  ammonium  sul- 
phid,  which  converts  the  nitrocompound  into  meta-di-amido-benzoic 
acid,  which  possesses  a  red  color  and  shows  immediately  on  the  sur- 
face of  the  fluid  without  stirring. 

If  any  two  of  these  methods  give  positive  reactions  it  is  safe  to 
assume  that  benzoic  acid  is  present.  The  methods  given  may  seem 
on  first  reading  to  be  slightly  complicated,  but  they  are  really  simple 
and  can  be  used  successfully  by  any  one  who  exercises  care. 

The  chloroform  and  ether  extraction  of  the  suspected  material 
will  show  in  the  final  tests  even  small  quantities  of  benzoic  acid. 

SALICVUC   ACID. 

In  1834  salicylic  acid  was  discovered  by  Pagensteecher  in  the 
flowers  of  Spiraea  Ulmaria,  in  the  form  of  salicyl  aldehyde.  This 
antiseptic  is  also  found  in  the  oil  of  wintergreen  (Gaultheria  pro- 
cumbens),  sweet  birch  (Betula  lenta)  and  other  varieties  of  gaul- 
theria, also  in  various  fruits  and  vegetable  roots.  It  is  obtained 
synthetically  from  carbolic  acid  or  phenol.  It  has  one  more  atom 
of  oxygen  than  benzoic  acid  and  its  symbol  is  C7HCO3.  It  is  also 
called  ortho-oxybenzoic  acid.  Kolbe  patented  a  process  for  obtain- 
ing it  by  treating  sodium  phenol  with  carbon  dioxide  gas.  Equal 
parts  were  evaporated  to  powder,  then  heated  to  212  degrees  F., 
then  a  stream  of  CO2  was  passed  over  it  and  temperature  raised  to 
365  degrees  F.,  then  to  428  degrees  F.,  then  to  482  degrees  F.,  until 
phenol  ceased  to  distill  over  the  retort.  One-half  of  the  phenol  re- 
mained and  formed  salicylate  of  sodium.  P.  W.  Hofman  patented 
a  process  by  which  all  the  phenol  was  converted  into  salicylic  acid  by 
using  superheated  steam  in  the  distillation. 

Salicylic  acid  is  a  snowy  white,  very  light  material,  comprised 
of  four-sided  prism,  which  crystallize  from  hot  water  in  fine  pris- 
matic needles.  It  has  a  sweetish  taste  and  an  acrid  after  taste.  It 
is  irritating  to  the  nostrils,  causing  violent  sneezing.  It  is  soluble 
in  450  parts  of  water  and  2^/2  parts  of  alcohol.  It  is  quite  soluble 
in  water  containing  8  per  cent  of  borax  or  10  per  cent  of  sodium 
phosphate. 

Salicylic  acid  is  one  of  the  benzyl  compounds,  of  which  there 
are  five  in  common  use.  All  have  the  peculiarities  of  the  base 
benzyl.  The  other  four  are  benzoic  acid,  benzaldehyde,  salol  and 
saccharin,  the  latter  being  intensely  sweet  and  is  sold  under  trade 
names  as  a  substitute  for  sugar,  to  which  it  has  no  chemical  analogy. 

Salicylic  acid  is  antiseptic  in  parts  i  to  1,000  (Miquel),  but  ex- 
erts marked  differences  on  various  bacteria.     Some  common  putre- 


CHEMICAL  ANTISEPTICS.  289 

factive  species  remain  unaffected  in  the  presence  of  considerable 
quantities,  while  others  perish,  and  this  accounts  for  the  losses  often 
experienced  when  salicyhc  acid  was  used  largely  as  a  preservative 
of  table  condiments  of  various  kinds.  This  chemical  came  into  fa- 
vor about  1880  and  the  quantities  imported  from  Germany  were 
enormous.  There  were  considerable  quantities  manufactured  in  the 
United  States,  but  the  acid  was  inferior  in  antiseptic  power  to  that 
of  the  imported.  Up  to  1894  it  continued  in  favor  and  was  used 
to  preserve  every  kind  of  food  subject  to  fermentation  and  putre- 
faction. Laws  were  rapidly  passed  prohibiting  its  employment  as 
a  food  preservative,  owing  to  the  statements  issued  by  several  au- 
thorities that  it  was  harmful  and  produced  heart  trouble  or  might 
cause  death  to  persons  having  heart  trouble,  and  so  it  was  replaced 
by  benzoic  acid,  neutralized  by  carbonate  of  sodium  and  sold  as 
benzoate  of  sodium. 

Salicylic  acid  is  combined  with  sodium  for  medicinal  purposes 
and  is  a  valuable  remedy  for  disordered  stomach,  due  to  fermenta- 
tion, also  for  rheumatism.,  etc.  It  is  easily  detected  by  the  official 
test  when  used  only  in  small  quantities. 

A  chloroform  or  ethereal  extract  is  made,  the  same  as  for  the 
benzoic  acid  test,  and  the  following  tests  are  reliable : 

First  Method. — Add  two  or  three  drops  of  ferric  chlorid  to  a 
small  quantity  of  the  extract  and  let  them  come  together  slowly. 
The  reaction  is  a  purple  or  violet  color. 

Second  Method. — Evaporate  0.5CC.  of  the  extract  to  dryness  at 
a  low  temperature,  and  add  one  drop  of  nitric  acid  (C.  P.),  then 
make  alkaline  with  a  few  drops  of  ammonia.  Ammonium  picrate  is 
form.ed,  having  a  yellow  color,  w^hich  may  be  used  to  dye  a  thread  of 
clean  wool. 

For  a  crude  test  the  presence  of  salicylic  acid  in  such  food  pro- 
ducts as  catsup.  Chili-sauce,  etc.,  may  be  determined  by  simply  dilut- 
ing the  material  with  water  and  using  a  few  drops  of  ferric  chlorid, 
which  produces  the  purple  or  violet  color.  The  simplicity  of  this 
test  was  a  cause  for  the  rapid  discontinuance  of  salicylic  acid  as  a 
preservative  after  the  laws  were  passed  prohibiting  it  In  foodstuff. 

FORMAI^DEHYDE. 

Formaldehyde  is  a  very  powerful  antiseptic  which  has  lately 
come  into  use,  especially  as  a  preservative  for  milk  and  some  other 
food  substances,  also  as  a  disinfectant  and  deodorizing  agent.  For- 
maldehyde is  symbolized  CHgO,  and  is  closely  allied  to  formic  acid, 
which  acid  results  from  oxidation.  It  was  discovered  in  1868  by 
Hofmann  and  was  made  by  passing  a  mixture  of  air  and  methyl- 
alcohol  (wood  alcohol)  vapor  over  heated  platinum.  It  is  prac- 
tically all  obtained  by  the  oxidation  of  methyl  alcohol.     This  is  ac- 


290  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

complished  in  ^'Formaldehyde  Lamps,"  a  platinum  cone  heated  by 
electricity.  It  is  a  gas  which  is  condensed  to  a  colorless  liquid  at  21° 
C,  and  at  a  higher  temperature  is  changed  into  paraformaldehyde, 
which  is  the  commercial  article  sold  for  preserving  purposes  in 
40  per  cent  solutions.  A  50  per  cent  solution  is  made,  but  is  un- 
stable. 

The  germicidal  power  of  formaldehyde  was  discovered  in  1888 
by  Traillat,  who  patented  a  process  for  manufacturing  it.  The 
germicidal  power  is  nearly  equal  to  that  of  corrosive  sublimate  and 
is  greater  than  that  of  carbolic  acid.  A  i  per  cent  aqueous  solution 
kills  all  spores  of  pathogenic  bacteria  in  one  hour.  It  decolorizes 
organic  matter,  precipitating  extracts  and  colors. 

It  is  a  strong  irritant  when  inhaled  and  afifects  the  mucous 
membrane  of  the  mouth  and  throat  and  inflames  the  nasal  passages ; 
the  gas  also  irritates  the  eyes  and  causes  them  to  smart  and  water. 
It  passes  through  the  body  when  taken  in  food  and  the  urine  does 
not  ferment ;  it  will  deodorize  faeces  or  putrefactive  products :  it  is 
an  excellent  disinfectant  and  may  be  heated  over  a  lamp  to  generate 
gas  for  disinfecting  rooms  after  cases  of  contagious  and  infectious 
diseases;  it  has  been  used  to  embalm  bodies  and  gives  firmness  to 
the  flesh. 

It  does  not  exert  a  very  great  germicidal  power  over  molds  and 
yeasts  and  for  this  reason  was  a  failure  as  a  substitute  for  salicylic 
acid  as  a  preservative  for  tomato  products,  such  as  catsup,  Chili- 
sauce,  chutney,  etc.  It  has  entered  into  the  composition  of  various 
"trade  preservatives"  and  has  thus  been  the  cause  of  considerable 
trouble  which  manufacturers  have  had  with  food  commissioners. 
The  manufacturers  have  been  purchasing  various  antiseptics  under 
trade  names  designated  by  numbers,  which  are  either  simple  or 
complex  antiseptic  chemicals,  and  are  put  up  and  sold  under  dis- 
guised names  at  four  to  ten  times  their  actual  value.  Many  of  these 
contain  formaldehyde,  benzoic  acid,  boric  acid  and  sometimes  sa- 
licylic acid  and  oftentimes  other  well-known  chemicals  which  have 
only  very  mild  antiseptic  power. 

Formaldehyde  is  probably  injurious  when  used  to  any  very 
great  extent  in  foods.  Owing  to  its  peculiar  nature  it  hardens  cel- 
lular and  albuminous  matter  and  should  not  be  used  as  a  preserva- 
tive for  meats,  fish  and  many  vegetables,  but  it  seems  to  preserve 
milk  I  to  15,000  for  a  few  days  without  any  serious  chemical 
changes. 

The  prevalence  of  this  chemical  in  nature  is  remarkable,  al- 
though the  amount  usually  present  in  various  plants  and  manufac- 
tured foods  is  perhaps  small.  It  is  present  in  many  of  the  growing 
plants ;  it  is  a  product  of  vital  action  of  bacteria  on  vegetable  mat- 
ter; it  is  found  frequently  in  fresh  milk  and  nearly  always  in  milk 


CHEMICAL  ANTISEPTICS.  291 

which  has  stood  exposed  to  the  action  of  bacteria.  Some  vegeta- 
bles, such  as  peas,  beans,  asparagus,  sugar  corn,  etc.,  when  allowed 
to  stand  exposed  to  the  air  before  canning,  will  give  the  chemical 
reaction  for  formaldehyde. 

Many  vegetables  and  meats,  when  processed  in  steam  retorts 
at  250°  F.,  show  the  presence  of  formaldehyde  by  the  official  test. 
At  this  place  I  wish  to  state  that  any  person  who  has  made  careful 
analyses  for  formaldehyde  in  nature  will  be  able  to  judge  whether 
the  reaction  is  due  to  an  added  chemical  or  merely  a  natural  forma- 
tion. While  there  is  no  reliable  official  quantitative  analysis,  yet  the 
analyst  should  be  able  to  tell  by  the  strength  of  the  reaction  whether 
formaldehyde  has  been  purposely  added  as  a  preservative  or  whether 
it  is  there  naturally  or  as  a  result  of  oxidation. 

There  are  some  substances  which  give  reactions  so  closely  re- 
sembling those  of  formaldehyde  that  the  analyst  must  be  extremely 
careful  in  forming  conclusions.  It  is  a  lamentable  fact  that  some 
of  our  agricultural  chemists  have  fallen  victims  to  both  of  the  wrong 
conclusions  cited.  It  has  been  suggested  that  perhaps  the  raw  ma- 
terial purchased  from  other  houses  probably  contained  formalde- 
hyde or  some  other  antiseptic,  and  the  food  manufacturer,  while  in- 
nocent of  adding  this  preservative  himself,  has  unconsciously  been 
guilty  of  statute  violation;  so  we  will  give  the  official  test  for  for- 
maldehyde to  enable  him  to  make  analyses  of  all  raw  material  used 
to  make  up  a  given  product. 

CHKMICAL  ANAIvYSIS  ^OR  F"ORMAr,DEHYDt:.       (w.  M.  AI.I,HN.) 

In  case  the  suspected  material  is  solid  or  semi-solid,  macerate 
from  200  to  300  grams  with  100  c.  c.  of  water  to  obtain  sufficient 
fluidity.  Make  this  preparation  distinctly  acid  with  phosphoric  acid 
and  fill  into  flask  of  500  to  800  c.  c.  capacity.  A  copper  flask  may  be 
heated  directly  over  flames  but  a  glass  flask  is  better  heated  in  a 
linseed  oil  bath.  Connect  flask  with  glass  condenser  and  distill  off 
about  40  or  50  c.  c. 

If  the  suspected  material  is  a  liquid  acidify  as  before  and  pro- 
cess as  directed  under  benzoic  acid  to  obtain  a  chloroform  or  ether 
extract,  which  is  distilled  in  oil  bath  at  250  to  260  degrees  F. 

METHOD  NO.   I. 

To  about  5  c.  c.  of  the  distillate  add  two  or  three  drops  of  a  i 
per  cent  aqueous  solution  phenol ;  mix  and  carefully  pour  it  on  about 
the  same  amount  of  sulphuric  acid  in  a  test  tube,  holding  tube  so 
that  the  solutions  will  not  mix.  The  presence  of  one  part  of  formal- 
dehyde in  100,000  parts  is  indicated  by  the  formation  of  a  crimson 
color  at  the  place  of  union  of  the  solutions.     If  formaldehyde  be 


292  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

present  in  greater  quantity  a  white  turbidity  or  a  light-colored  pre- 
cipitation will  be  formed  above  the  coloring. 

If  organic  matter  is  distilled  over  the  charring  of  it  by  the  sul- 
phuric acid  may  be  mistaken  for  a  trace  of  formaldehyde,  but  on 
allowing  the  test  to  stand  for  twelve  hours  the  coloration  due  to 
the  formaldehyde  will  become  a  whitish  turbidity  instead  of  the  dark 
color  which  appears  if  due  to  the  charring  of  organic  matter. 

Note. — Some  other  aldehydes  will  give  the  same  result  and  it 
is  not  therefore  conclusive. 

METHOD   NO.    2. 

Add  about  5  c.  c.  of  the  distillate  obtained  originally  to  an 
equal  volume  of  pure  milk  in  a  casserole,  also  10  c.  c.  of  muriatic 
acid  (C.  P.)  containing  i  c.  c.  of  a  10  per  cent  solution  of  ferric 
chlorid  solution  to  each  500  c.  c.  of  acid.  Heat  to  80°  or  90°  di- 
rectly over  flame,  giving  casserole  a  rotary  motion  to  break  up  the 
curd  of  the  milk.     A  violet  color  may  indicate  formaldehyde. 

;  METHOD    NO.    3. 

Dissolve  I  gram  of  phenyl hydrazin  hydrochlorid  and  i^ 
grams  acetate  of  sodium  in  10  c.  c.  of  water.  To  i  c.  c.  of  distil- 
late obtained  originally  add  2  drops  of  reagent  and  2  drops  of  sul- 
phuric acid.     A  green  color  indicates  the  presence  of  formaldehyde. 

BORACIC  ACID  OR  BORIC  ACID. 

Boric  acid  is  a  preservative  used  for  milk,  meats  and  veget- 
ables. Various  preparations  of  boric  acid  or  borates  are  sold  under 
trade  names  as  food  preservatives.  A  mixture  of  boric  acid 
and  borax  was  sold  under  the  name  of  "Rex  Magnus;"  another 
mixture  of  boric  acid  and  glycerol  is  sold  under  the  name  of  "Boro- 
glycerid.'' 

Boric  acid  is  symbolized  as  H3BO3  and  is  obtained  by  the  inter- 
action of  sulphuric  acid  (H2SO4),  and  borax  (NaoB^Oy),  also  by 
the  purification  of  native  boric  acid,  found  in  combinations  as  a  mag- 
nesium salt  in  sea  water,  mineral  waters,  such  as  Vichy,  AViesbaden 
and  Aix-la-Chapel ;  also  in  mineral  substances,  as  boro-calcite  in  the 
niter  beds  of  Chili ;  also  in  natural  borax  or  tincal  in  the  dried-up 
lagoons  in  central  Asia;  in  large  quantities  in  Clear  Lake,  Califor- 
nia. It  is  found  in  ulexite  (sodium  and  calcium  borate)  and  cole- 
manite  (calcium  borate),  also  found  in  a  large  vein  deposit,  prob- 
ably of  volcanic  origin  in  San  Bernardino  County,  California,  which 
yields  about  twenty-five  million  pounds  annually. 

Boric  acid  occurs  as  pearly  scales  soluble  in  water  and  alcohol, 
has  a  feeble  acid  reaction  and  possesses  a  bitter  taste.     It  changes 


CHEMICAL  ANTISEPTICS.  293 

to  metaboric  acid  (HBO2)  when  heated  to  250°  F.  and  may  be 
changed  by  further  heating  to  its  anhydrid,  B2O3. 

As  an  antiseptic  it  has  very  httle  vahie  and  has,  I  think,  been 
very  much  over-estimated,  altliough  it  is  used  with  fair  success  for 
preserving  milk.  When  combined  with  other  salts  it  seems  to  re- 
tard putrefaction  in  meats,  sausages,  butter  and  milk.  It  is  never 
used  in  sufficient  quantities  to  be  germicidal,  hence  pathogenic  bac- 
teria, such  as  typhoid,  anthrax,  hog  cholera,  tuberculosis,  etc.,  will 
remain  alive,  though  dormant,  in  meats  lightly  cured  and  in  butter 
made  from  infected  cream. 

Much  of  our  exported  meat,  butter  and  other  foodstuff  is  par- 
tially preserved  with  boric  acid,  and  this  seems  to  be  necessary  for 
countries  which  are  not  advanced  in  refrigerating  methods.  Our 
manufacturers  use  large  quantities,  therefore,  in  expert  goods  to 
prevent  reclamations  on  account  of  spoilage.  This  is  not  so  neces- 
sary in  our  country,  because  we  have  means  of  preserving  such 
foods  in  refrigerators  or  cold  storage. 

As  a  preservative  for  catsup.  Chili-sauce,  chutney,  jams,  jellies, 
preserves,  etc.,  boric  acid  has  very  little  value.  When  Barff  dis- 
covered ''boro-glycerid"  in  1886  it  was  hoped  that  it  might  be  a 
valuable  harmless  antiseptic  for  tomato  products,  but  the  tests  did 
not  give  satisfaction. 

Boric  acid  is  antiseptic  in  i  part  to  300. 

OI^FICIAI.  CHEMICAL  TEST  FOR  BORIC  ACID. — NO.    I,  QUALITATIVE 

ANALYSIS. 

Render  decidedly  alkaline  with  lime  water  about  25  grams  of 
the  sample  evaporate  to  dryness  on  a  water  bath.  Ignite  the  resi- 
due to  destroy  organic  matter.  Add  about  15  c.  c.  of  water  and 
hydrochloric  acid,  drop  by  drop,  to  acid  reaction.  Then  add  about 
I  c.  c.  of  concentrated  hydrochloric  acid.  Moisten  a  piece  of  deli- 
cate tumeric  paper  with  the  solution ;  if  borax  or  boric  acid  is  pres- 
ent the  paper  on  drying  will  acquire  a  peculiar  red  color,  which  is 
changed  by  ammonia  to  a  dark  blue-green,  but  is  restored  by  acid. 
This  color  is  almost  unmiistakable,  but  it  is  best  for  one  not  familiar 
with  it  to  conduct  a  test  where  boric  acid  is  known  to  be  present. 

NO.  2. — QUALITATIVE  ANALYSIS.       (oEl^ICIAL.) 

y\dd  an  equal  drop  of  fresh  saturated  tumeric  tincture  and  a 
drop  of  h3^drochloric  acid  and  heat  for  a  few  seconds. 

If  the  suspected  material  be  a  liquid,  evaporate  with  the  tumeric 
and  heat  with  a  drop  of  diluted  hydrochloric  acid  for  a  few  seconds ; 
then  if  borax  or  boric  acid  be  present  a  pink  or  dark  red  color  will 
appear,  depending  upon  the  quantity  present.  Cool  and  add  a  drop 
of  ammonium  hydroxid,  when  a  dark  blue-green  color  will  appear. 


294 


CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


MIQUElv'S   TABLE    OF   ANTISEPTICS. 

Miquel  made  tests  of  a  large  number  of  substances  to  ascertain 
their  antiseptic  value,  many  are  powerful  poisons  for  man  as  well  as 
bacteria.  There  are  quite  a  number  whose  action  on  the  human 
organism  are  not  positively  known,  and  there  are  quite  a  number 
which  have  only  very  slight  antiseptic  power.  The  most  common 
powerful  antiseptic  and  disinfectant  in  general  use  for  destroying 
bacteria  on  instrument,  furniture,  and  various  materials,  which  do 
not  come  in  contact  with  food,  is  mercuric  chlorid,  or  corrosive  sub- 
limate. This  is  used  largely  in  our  laboratories  for  destroying  cul- 
tures of  bacteria,  or  for  disinfecting  purposes.  We  give  Miquel's 
table  of  antiseptics  and  their  proportions  which  prove  effective. 


SUBSTANCES  EMINENTLY  ANTISEPTIC. 


Mercuric  iodid   

Silver  iodid 

Hydrogen  peroxid  (this  is  unstable) 

Mercuric  chlorid 

Silver  Nitrate 


part  in  40,000 

"   "  33'000 

"       "  20,000 

"       ''  14,300 

''  12,500 


SUBSTANCES  VERY   STRONGLY  ANTISEPTIC. 

Osinic  Acid i  part  in  6,666 

Chromic  Acid i  ''  ''  5,000 

Chlorine    i  "  "  4^000 

Iodine    i  ''  ''  4,000 

Chlorid  of  Gold i  "  "  4,000 

Bichlorid  of  Platinum i  "  "  3'333 

Hydrocyanic  Acid  (Prussic  Acid) i  "  "  2,560 

Bromine    i  "  "  1,666 

Cupric  Chlorid   i  "  "  1,428 

Thymol   I  "  "  1,340 

Cupric  sulphate       i  "  "  1,1 1 1 

Salicylic  Acid   i  "  ''  1,00  o 


SUBSTANCES  STRONGLY  ANTISEPTIC. 

Benzoic  Acid i   part  in 

Potassium  Bichromate    i 

Potassium  Cyanid i 

Aluminum  Chlorid i 

Ammonia    i 

Zinc  Chlorid i 

Mineral  Acids i 

Thymic  Acid t 


909 

909 

909 

714 

714 

526 

500  to  333 

500 


CHEMICAL  ANTISEPTICS. 


295 


Lead  Chlorid 

Nitrate  of  Cobalt 

Sulphate  of  Nickel 

Nitrate  of  Uranium 

Carbolic  Acid  .  /. 

Potassium  permanganate 

Lead  Nitrate 

Alum   

Tannin    


Bromhydrate  of  Quinine 

Arsenious  Acid    

Boracic  Acid 

Sulphate  of  Strychnia  .  .  , 

Arsenite  of  Soda 

Hydrate  of  Chloral   .  .  .  . 
Salicylate  of  Sodium   .  .  . 

Ferrous  Sulphate 

Caustic  Soda 


SUBSTANCES  I^EEBLY  ANT 


Perchloride  of  Manganese 

Calcium  Chloride 

Sodium  Borate 

Muriate  of  Morphia 

Strontium  Chloride   

Lithium  Chloride 

Barium  Chloride 

Alcohol   


Ammonium  Chlorid  . .  .  . 
Potassium  Arsenite   .  .  .  . 

Potassium  lodid 

Sodium  Chlorid   

Glycerine  (sp.  gr.  1.25.) 
Ammonium  Sulphate  .  . 
Sodium  Hyposulphite  .  .  , 


500 

a 

476 

a 

400 

(( 

356 

(I 

333 

a 

285 

a 

277 

11 

222 

(( 

207 

^NTISEP 

I   part 

ric. 
in 

182 

u 

166 

l( 

143 

i( 

143 

ii 

III 

li 

107 

11 

100 

(I 

90 

11 

56 

ISEPTIC 

I  part 

in 

40 

(< 

25 

a 

14 

a 

13 

a 

12 

a 

II 

a 

10 

(( 

10 

NTISEPTIC. 

I  part 

in 

9 

8 

7 

6 

4 

4 

3 

A  careful  study  of  this  table  shows  that  the  antiseptics  usually 
employed  in  foodstuff  are  equally  effective  with  some  of  the  most 
powerful  mineral  poisons  known.  Miquel  places  hydrogen  perox- 
id  as  third  in  the  list  of  antiseptics  eminently  powerful.    If  this 


296  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

preparation  were  stable  it  could  be  used  almost  ad  libitum,  because 
it  is  not  poisonous,  but  it  loses  its  properties  rapidly  and  soon  de- 
composes into  water  by  giving  up  one  atom  of  oxygen,  thus  H.,09 — 
O^HsO. 

From  our  experience  with  this  substance  we  are  inclined  to 
think  that  Miquel  overestimated  its  value  as  an  antiseptic.  It  does 
not  prove  effective  as  a  food  preservative.  Nearly  all  my  experi- 
ments have  failed,  even  when  the  proportion  used  was  i-i,ooo. 
This  may  be  due  to  its  unstable  nature,  and  cannot  therefore  be 
satisfactory. 


ARTIFICIAL  SWEETENERS  AND  ADULTERANTS.  297 

CHAPTER  X. 

Artificial  Sweeteners  and  Adulterants 

Saccharin.  Methods  of  Detection.  Dulcin.  Methods  of  Detec- 
tion. Ghicin.  Sulphites.  Methods  of  Detection.  Artificial 
Colors.     Starch,  etc. 


SACCHARIN. 


Saccharin  is  the  commercial  name  for  Glusidum,  or,  according 
to  the  British,  the  drug  name  is  given  as  Gluside;  the  chemical 
name  is  benzo}^  sulphonimide,  which  gives  some  clue  to  its  base  ori- 
gin. It  is  a  sweet  imide,  from  toluene,  and  is  symbolized  as  C.7H5. 
NSOy.  It  is  obtained  by  first  converting  toluene  into  sulphamide, 
w^hich  by  oxidation  yields  the  imide.  It  forms  a  white  powder 
which  melts  392°  P.,  with  partial  decomposition,  evolving  the 
odor  of  bitter  almonds.  It  is  soluble  in  water,  from  which  it  may 
be  crystallized  in  alcohol,  ether,  glycerin  and  .clucose.  Saccharin 
may  be  detected  in  solutions  containing  sugar,  by  extracting  with 
ether,  then  evaporating  and  fusing  the  residue,  which  will  melt  at 
about  392°  P.,  and  if  fused  with  nitre  and  carbonate  of  sodium,  will 
show  sulphuric  acid.  The  weight  of  BaS04  obtained  in  this  way 
from  TOO  grams  of  sugar  multiplied  by  0.785  will  give  weight  of 
saccharin  extracted. 

Saccharin  occurs  as  a  white  powder  composed  of  irregular 
crystals  only  slightly  soluble  in  water,  readily  soluble  in  glycerine, 
alcohol  and  ether.  The  aqueous  solution  has  a  distinct  acid  reac- 
tion and  forms  salts. 

The  commercial  saccharin  contains  para-sulphamine-benzoic 
acid,  from  which  impurity  it  may  be  freed  by  recrystallization,  ace- 
tone being  used  as  the  solvent.  The  difference  in  the  melting  point 
between  saccharin  and  para-sulphamine-benzoic  acid  is  also  used 
for  distinguishing  them.  The  pure  chemical  saccharin  melts  at 
286.5°  ^-^  while  the  other  melts  at  224.5°  ^' 

Saccharin  is  very  soluble  in  weak  solution  of  ammonia,  also  in 
bicarbonate  of  sodium. 

Saccharin  has  no  properties  of  sugar  except  sweetness;  it  has 
no  food  value,  and  passes  unchanged  through  the  kidneys,  and  will 
prevent  to  some  extent  ammoniacal  fermentation  of  the  urine. 

As  an  antiseptic  it  has  very  little  value,  and  is  not  used  in  food 
products  for  preserving  or  preventing  fermentation.     Wherever  it 


298  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

is  used,  the  object  is  to  take  the  place  of  sugar.  It  is  generally  re- 
garded by  Pure  Food  Authorities  as  an  adulterant,  and  this  is  one 
construction  that  can  be  put  upon  its  employment  in  food  products. 
That  it  is  used  in  large  quantities  for  sweetening  glucose,  syrups, 
preserves,  jams,  jellies  and  canned  goods,  such  as  corn  and 
peas,  cannot  be  denied.  The  consumers  in  all  cases,  no  doubt,  be- 
lieve that  their  goods  owe  their  sweetness  to  sugar,  and  are  thus 
deceived  and  are  deprived  of  the  food  which  they  believe  they  are 
purchasing,  sugar  being  a  food  and  saccharin  having  no  food  value. 
There  are  large  quantities  of  syrups  almost  worthless  as  such,  which 
are  sweetened  with  saccharin  and  sold  at  fair  prices,  the  consum- 
ers believing  same  to  be  the  product  of  cane  sugar. 

There  are  many  authors  quoted  on  each  side  of  the  question, 
"Is  saccharin  injurious  to  the  human  organism?"  and  it  is  not  with- 
in the  province  of  this  work  to  enter  into  the  discussion,  but  we 
believe  that  the  preponderance  of  evidence  is  unfavorable  to  its  em- 
ployment as  a  sweetener  of  food  products.  Among  the  authorities 
who  write  against  it,  might  be  quoted  Dr.  Wiley,  Chief  Chemist  of 
the  United  States,  Thomson,  Sollman,  Dr.  Butler,  Dr.  C.  H.  Wood 
and  Paul.  These  authorities  claim  that  "Saccharin  checks  the 
action  of  ptyalin,  pepsin,  trypsin  and  other  allied  ferments,"  that 
"it  increases  the  amount  of  chlorides  excreted  from  the  urin,"  that 
"it  has  no  food  value;  it  is  an  antiseptic;  it  prevents  decay,  and 
therefore  retards  digestion  to  that  extent."  It  is  believed  by  some 
that  its  long  continued  use  may  give  rise  to  nephritis. 

From  the  knowledge  that  we  possess,  viz.,  its  employment  as  a 
substitute  for  cane  sugar,  and  the  possible  injurious  effects  which 
it  may  have  upon  the  human  organism,  it  seems  wise  that  every 
packer  of  foodstuff  eliminate  saccharin  and  make  every  effort  to  ele- 
vate the  standard  of  their  goods  by  using  only  cane  sugar  as  a 
sweetener. 

There  are  several  tests  wdiich  are  used  to  determine  the  pres- 
ence of  saccharin,  and  the  packers  who  use  syrups  in  their  formu- 
las may  determine  its  presence  as  follows : 

If  the  sample  to  be  tested  is  a  solution  or  syrup,  render  it  acid, 
if  not  already  such,  with  phosphoric  acid,  and  extract  with  ether. 
In  case  of  canned  vegetables  and  similar  goods,  finely  divide  the 
material  by  pulping  or  maceration  in  a  mortar,  dilute  with  water, 
and  strain  through  muslin.  Acidify  the  filtrate,  and  extract  wnth 
ether.  If  an  emulsion  forms,  use  a  centrifugal  machine.  Separ- 
ate the  extract,  evaporate  off  the  ether,  and  test  the  residue  for  sac- 
charin as  follows : 

(i)  Add  to  the  residue,  if  it  tastes  sweet,  a  few  cubic  centi- 
meters of  hot  water,  or  preferably  a  very  dilute  solution  of  sodium 
carbonate,  in  which  saccharin  is  more  soluble.     An  intensely  sweet 


ARTIFICIAL  SWEETENERS  AND  ADULTERANTS.  299 

taste  is  indicative  of  its  presence.  This  test,  if  applied  directly,  will 
sometimes  fail,  especially  in  the  case  of  beer,  by  reason  of  the  extrac- 
tion of  ether  of  various  bitter  principles,  such  as  hop  resins,  which 
by  their  strong,  bitter  taste  mask  the  sweet  taste  of  saccharin  in 
the  residue.  Speath  recommends  that  such  bitter  substances  be  re- 
moved before  extraction,  which  is  done  by  treatment  of  500  c.  c. 
of  the  beer  with  a  few  crystals  of  copper  nitrate,  or  with  a  solution 
of  copper  sulphate.  The  flocculent  precipitate  formed  need  not  be 
filtered  off,  but  the  liquid  is  preferably  concentrated  by  evaporation 
to  syrupy  consistency,  acidified  with  phosphoric  acid,  and  extracted 
with  three  successive  portions  of  a  mixture  of  ether  and  petroleum 
ether.  After  extraction,  separation,  and  evaporation  of  the  sol- 
vent, dissolve  the  residue  in  weak  sodium  carbonate.  As  small  a 
quantity  as  0.00 1  per  cent  of  saccharin  can  be  detected  in  the  final 
alkaline  solution  bv  its  sweet  taste. 

(2)  Bornstein's  Test. — Heat  the  residue  from  the  ether  extrac- 
tion of  the  acidified  sample  with  resorcin  and  a  few  drops  of  sul- 
phuric acid  in  a  test  tube  till  it  begins  to  swell  up.  Remove  from 
the  flame,  and,  after  cooling  till  the  action  quiets  down,  again  heat, 
repeating  the  heating  and  cooling  several  times.  Finally  cool,  di- 
lute with  water,  and  neutralize  with  sodium  hydroxid.  A  red- 
green  fluorescence  indicates  saccharin.  Gantter  states  that  it  is 
useless  to  apply  this  test  to  beer,  in  view  of  the  fact  that  ordinary 
hop  resin  gives  the  same  fluorescence. 

(3)  Schmidt's  Test. — The  residue  is  heated  in  a  porcelain  dish 
with  about  a  gram  of  sodium  hydroxid  for  half  an  hour  at  a  tem- 
perature of  250^  C,  either  in  au  air-oven  or  in  a  linseed  oil  bath. 
This  converts  the  saccharin  if  present  into  sodium  salicylite.  Dis- 
solve the  fused  mass  in  water,  acidify,  and  extract  the  solution  with 
ether.  Test  the  ether  residue  in  the  regular  manner  for  salicylic 
acid  with  ferric  chlorid.  This  test  can  obviously  be  applied  only  in 
the  absence  of  salicylic  acid,  which  should  first  be  directly  tested  for. 

DULCIN. 

This  white  powder  is  composed  of  needle-like  crystals,  slightly 
soluble  in  cold  water,  ether  and  chloroform.  Its  symbol  is  CgHjoNg 
O2.  It  is  soluble  in  800  parts  of  cold  water,  50  parts  of  boiling 
water,  and  25  parts  of  95  per  cent  alcohol.  It  is  soluble  in  acetic 
ether.     Dulcin  is  about  four  hundred  times  as  sweet  as  cane  sugar. 

When  dulcin  is  combined  with  N/jo  sodium  hydroxid  and  sub- 
jected to  distillation,  a  substance  called  phenetidin  is  formed  which 
volatilizes  and  passes  into  the  distillate.  This,  when  heated  with 
glacial  acetic  acid,  forms  phenacetin.  Phenacetin  is  detected  by 
first  boiling  with  hydrochloric  acid,  diluting  with  water,  cooling  the 
filtrate,  and  adding  a  few  drops  of  chromic  acid  solution.  A  deep 
red  color  is  formed. 


300  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

DETECTION  OF  DULCIN. 

(i)  Bellier's  Method. — A  portion  of  the  sample  to  be  tested 
is  made  alkahne  and  extracted  with  acetic  ether.  In  the  case  of 
certain  products  it  is  best  to  subject  them  to  varied  prehminary 
treatment,  depending  on  the  case  in  hand.  With  such  products  as 
thin  fruit  syrups,  simply  make  alkaline  and  shake  out  with  acetic 
ether.  In  the  case  of  thick  fruit  syrups,  confectionery  and  pre- 
serves, dilute  with- water,  add  an  excess  of  basic  lead  acetate,  remove 
the  lead  by  precipitation  with  sodium  sulphate,  filter  and  make  the 
filtrate  alkaline. 

Having  thus  obtained  a  clarified  solution,  use  from  50  to  200 
c.  c.  of  neutral  acetic  ether  to  say  500  c.  c.  of  the  alkaline  solution, 
and  shake  in  a  separatory  funnel.  Separate  the  extract,  filter,  and 
evaporate  to  dryness.  If  the  dulcin  exceeds  0.04  gram  per  liter ,^ 
crystals  will  be  apparent  in  the  residue.  If  fats  and  resins  are  pres- 
ent in  the  residue,  make  repeated  extractions  w'ith  hot  water,  and 
evaporate  to  dryness.  The  purified  residue  is  finally  brought  to  dry- 
ness in  a  porcelain  dish,  and  treated  wnth  i  or  2  c.  c.  of  sulphuric 
acid  and  a  few  drops  of  a  solution  of  formaldehyde.  Let  it  stand 
for  fifteen  minutes,  and  afterwards  dilute  with  5  c.  c.  of  w^ater.  A 
turbidity  or  precipitate  indicates  dulcin. 

(2)  Jorissen's  Test. — The  residue  from  the  acetic  ether  ex- 
tract of  an  alkaline  solution  of  the  sample  is  treated  with  2  or  3  c.  c. 
of  boiling  w^ater  in  a  test-tube,  and  a  few  drops  of  mercuric  nitrate 
are  added.  Heat  the  tube  and  its  contents  for  five  minutes  in  a 
boiling  water  bath,- withdraw,  and  disregarding  any  precipitate,  add 
a  small  quantity  of  lead  peroxide.  On  the  subsidence  of  the  precip- 
itate, which  quickly  occurs,  a  fine  violet  color  appearance  forms  for 
a  short  time  in  the  clear  upper  layer  in  presence  of  o.ooi  gram,  of 
dulcin. 

(3)  Morpurgo's  Method. — To  the  acetic  ether  residue,  eva- 
porated to  dryness  in  a  porcelain  dish,  add  a  few  drops  of  phenol 
and  concentrated  sulphuric  acid,  and  heat  a  few  minutes  on  the 
water-bath.  After  cooling,  transfer  to  a  test-tube,  and  with  the  least 
possible  mixing  pour  ammonia  or  sodium  h3^droxid  over  the  sur- 
face. A  blue  zone  at  the  plane  of  contract  between  the  two  layers, 
indicates  dulcin. 

GT^UCIN. 

This  is  a  light-brown  powder  soluble  in  water,  but  not  in  ether 
and  chloroform.  It  is  three  hundred  times  sweeter  than  cane  sugar. 
Its  symbol  is  C19H1CN4. 


ARTIFICIAL  SWEETENERS  AND  ADULTERANTS.  301 

DETECTION   OE  GLUCIN. 

Dissolve  in  dilute  hydrochloric  acid  and  cool,  then  add  a  few 
■drops  of  sodium  nitrite  solution,  followed  by  a  few  drops  of  an 
alkaline  solution  or  beta-napthol.  A  red  color  is  produced.  If  re- 
sorcin  or  salicylic  acid  is  used  instead  of  beta-napthol,  the  color  will 
be  yellow. 

SULPHITES. 

Sulphurous  acid,  H^SOo,  in  the  form  of  SO2,  sulphur  dioxid, 
is  combined  with  soda  and  used  as  a  preservative  and  as  a  bleaching 
agent.  The  sulphites  are  bisulphite  of  soda  and  hyposulphite  of 
soda,  the  former  being  used  largely  in  preserving  meats  and  as  a 
bleaching  agent  for  corn  and  asparagus,  also  all  kinds  of  dried 
fruits.  Sulphur  dioxide  is  widely  distributed  in  nature  and  is  pres- 
ent in  minute  quantities  in  various  fruits  and  vegetable,  and  qualita- 
tive analytical  tests  for  its  presence  must  show  more  than  a  trace  in 
order  to  establish  the  fact  that  it  has  been  employed  as  a  preserving 
or  bleaching  agent.  That  this  substance  is  harmful  to  the  human  or- 
ganism is  doubtful.  The  quantity  which  may  be  used  in  food  pro- 
ducts is  necessarily  small  since  it  imparts  a  sulphurous  taste  if  used 
in  excess.  That  sulphites  are  necessary  in  any  branch  of  the  food 
industry  is  doubtful.  Corn  bleached  with  them  becomes  tasteless 
and  loses  a  great  deal  of  its  flavor ;  asparagus  is  better  with  a  nat- 
ural color.  Used  as  a  bleach  for  evaporated  fruits  it  may  appear  to 
be  necessary,  but  if  the  public  be  educated  to  accept  the  natural  fruit, 
its  necessity  will  disappear.  As  a  preventive  of  mold  sulphurous 
acid  is  effective  and  may  be  recommended  for  cleansing  the  pack- 
ages and  utensils  employed  in  the  food  industry. 

For  the  detection  of  sulphites  we  give  the  official  test,  so  that 
packers  may  analyze  their  own  raw  materials  procured  from  outside 
sources.  A  microscopical  inspection  will  show  the  presence  of  the 
crystals  on  raisins,  currants,  citron,  etc.,  used  in  mince-meat  and 
other  preparations.  If  the  sulphites  are  present  on  the  raw  ma- 
terial, of  course  the  finished  product  will  give  the  chemical  reactions 
and  may  be  condemned  by  the  food  commissioners. 

METHOD  NO.   I — BY  DISTILLATION. 

Place  50  grams  of  the  material  in  a  distilling  flask,  add  about 
5  c.  c.  of  a  saturated  solution  of  glacial  phosphoric  acid,  add  enough 
distilled  water  to  make  up  100  c.  c,  and  distil  in  a  current  of  carbon 
dioxid  until  50  c.  c.  have  passed  over.  Take  a  few  c.  c.  of  the  distil- 
late, add  a  slight  excess  of  iodin  solution,  boil  to  expel  excess  of 
iodin,  then  acidify  with  hydrochloric  acid  and  add  barium  chlorid 
solution.     This  test  is  very  delicate  and  is  easily  applied. 


302               CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 
METHOD   NO.    2 BY   RHDUCTlON. 

To  about  25  grams  of  the  sample  placed  in  a  200  c.  c.  Erlen- 
meyer  flask,  add  some  pure  zinc  and  several  cubic  centimeters  of 
hydrochloric  acid.  In  the  presence  of  sulphites,  hydrogen  sulphid 
will  be  generated  and  may  be  detected  by  lead  paper.  Traces 
of  metallic  sulphids  are  occasionally  present  in  vegetables,  and  by 
the  above  test  will  indicate  sulphites.  Hence  positive  results  ob- 
tained by  this  method  should  be  verified  by  the  distillation  method. 

It  is  always  advisable  to  make  the  quantitative  determination  of 
sulphites,  owing  to  the  danger  that  the  test  may  be  due  to  traces 
of  sulphids.  A  trace  is  not  to  be  considered  sufficient  evidence  that 
a  sulphite  has  been  used  either  as  a  bleaching  agent  or  as  a  preser- 
vative. 

The  chemicals  described  are  those  principally  employed  as  pre- 
servatives of  food.  There  are  many  more  powerful  in  their  germi- 
cidal power  than  these,  but  are  either  known  poisons  or  are  unstable 
and  consequently  cannot  be  employed  as  food  preservatives.  There 
are,  however,  various  materials  used  in  preparing  raw  materials 
and  even  finished  products,  which  are  preservatives  in  a  slight  de- 
gree, although  not  always  employed  for  that  purpose.  Comm.on 
salt  is  a  mild  preservative  and  if  used  in  the  form  of  brine  restricts 
fermentation,  allowing  only  certain  microorganisms  to  flourish, 
which  generally  belong  to  the  lactic  acid  group,  while  the  bacteria 
which  elaborate  foul  products  and  gases  are  completely  checked, 
first  by  the  salt,  and  then  by  the  lactic  acid  formed. 

Sugar,  when  used  Jn  sufficient  quantities,  is  a  preservative,  be- 
cause it  rapidly  takes  up  the  fluids  to  form  syrups,  and  all  bacteria 
are  deprived  of  the  moisture  so  necessary  for  reproduction  or  vege- 
tation. Small  quantities  of  sugar  have  no  antiseptic  value,  since  the 
carbon  is  rapidly  utilized  to  supply  that  element  so  necessary  for  the 
development  of  cell  protoplasm,  of  bacteria.  Thus  small  quantities 
of  sugar  are  favorable  to  the  growth  of  yeasts  and  molds,  also  vari- 
ous species  belonging  to  the  schizomycetes  or  fission  fungi.  Sugar, 
when  split  up  by  fermentation  set  up  by  yeasts  and  molds,  is  con- 
verted into  alcohol,  glycerin,  carbonic  acid,  succinic  acid,  and  other 
fatty  acids,  or  it  may  be  attacked  by  lactic  acid  bacteria  and  be 
split  up  into  lactic  acid  without  the  evolution  of  gas.  Sugar,  when 
used  as  a  heavy  syrup,  is  antiseptic  to  a  considerable  degree,  since 
most  bacteria  cannot  obtain  sufficient  fluid  to  form  new  protoplasm. 

Acetic  acid  is  employed  as  a  preservative  in  the  form  of  vine- 
gar, but  some  vinegars  containing  large  quantities  of  organic  mat- 
ter, do  not  possess  much  antiseptic  power.  Some  vinegars  are  them- 
selves easily  attacked  by  bacteria  and  their  acetic  acid  is  changed 
to  carbonic  acid  and  water.  The  best  pickling  vinegar  is  white 
wine,  obtained  by  distillation; cider,  malt  and  fruit  vinegars  are  very 


ARTIFICIAL  SWEETENERS  AND  ADULTERANTS.  303 

susceptible  to  changes  if  exposed  to  warm  temperatures.  The  5 
per  cent  white  wine  vinegar  has  antiseptic  power  and  is  largely  used 
in  all  pickled  goods. 

ARTIFICIAL  COLORS. 

There  are  several  reasons  given  by  some  manufacturers  for 
the  employment  of  artificial  colors  to  brighten  their  goods;  some 
claim  that  the  uncolored  product  does  not  look  appetizing,  therefore 
it  should  be  colored  just  enough  to  please  the  eye.  In  a  sense  we 
all  eat  with  our  eyes,  and  it  is  a  question  whether  food  has  the  same 
value  if  it  does  not  appeal  to  the  eye.  Several  experiments  have 
been  tried  upon  animals  by  feeding  them  blindfold  and  the  results 
gave  evidence  that  the  food  did  not  accomplish  its  full  value,  for 
the  animals  grew  weak  and  emaciated.  Some  claim  that  colors 
should  be  used  to  cover  up  certain  defects  which  cannot  be  avoided 
in  present  methods  of  manufacture.  This  claim  is  based  on  the 
discoloration  of  raw  material,  which  is  stored  away  in  barrels  and 
other  wooden  packages.  It  is  claimed  that  during  the  busy  sea- 
son the  fresh  products  from  the  farms  are  delivered  to  the  packers 
much  faster  than  they  can  be  worked  into  finished  goods,  and  this 
necessitates  the  storing  of  partially  prepared  material  in  barrels  and 
casks,  until  such  time  as  may  be  more  convenient  for  finishing.  The 
tannic  acid  from  the  wood  discolors  this  material  very  much,  and  the 
packers  claim  that  it  is  necessary  to  restore  its  natural  appearance  by 
adding  certain  coal  tar  dyes  which  give  the  finished  product  the  ap- 
pearance of  freshly  prepared  stock. 

We  all  know  that  vegetables  and  some  fruits  lose  some  of  their 
natural  color  during  the  heating  which  is  necessary  to  properly 
sterilize  them;  in  some  cases  the  color  is  changed  slightly,  though 
not  faded ;  corn  is  an  example  of  this.  Peas,  string  beans,  aspara- 
gus, catsup.  Chili-sauce,  tomato  chutney,  fruit  juices  and  many  other 
raw  materials  lose  a  certain  amount  of  their  natural  color  in  the 
sterilizing  process  and  in  the  cooking  or  evaporating  methods,  but  if 
these  materials  are  prepared  properly  they  will  still  retain  enough  of 
their  original  color  to  appeal  to  the  palate,  and  do  not  need  the  ad- 
dition of  coal  tar  dyes  or  other  colors  to  replace  the  smalh  amount 
of  natural  color  lost  during  the  preparation. 

Packers,  who  contract  for  more  raw  material  than  they  are 
able  to  make  up  into  finished  goods,  should  not  try  to  imitate  first- 
class  goods  with  the  surplus  material  which  they  are  forced  to  ac- 
cept, unless  they  have  some  good  method  for  keeping  it.  No  packer 
should  contract  for  more  raw  material  than  he  is  able  to  handle 
properly,  and  if  he  does  receive  more  and  is  forced  to  save  it  by 
partial  cooking  and  storing  In  wooden  packages,  he  should  expect 


304  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

to  sell  same  for  its  true  value,  and  not  attempt  to  bring  up  the 
standard  by  artificial  colors.  Now  to  make  this  clear,  we  will  take 
for  example  one  packer  who  contracts  just  what  tomatoes  he  thinks 
he  is  able  to  make  up  into  catsup,  Chili-sauce,  etc.,  during  the  season 
and  he  employs  all  the  help  that  is  necessary  to  finish  the  goods  and 
bottle  same  without  having  to  store  away  any  pulp,  in  other  words, 
he  invests  at  once  in  everything  necessary  to  finish  and  take  care  of 
his  daily  receipts  of  raw  material,  and  has  that  investment  tied  up 
for  six  or  eight  month ;  his  goods  are  not  artificially  colored  nor  do 
they  need  to  be,  and  the  quality  will  be  the  very  best,  but  he  goes 
into  the  market  and  finds  goods  just  as  bright,  or  perhaps  brighter 
than  his,  which  have  been  prepared  from  barreled  stock  and  arti- 
ficially colored.  The  consumer,  who  does  not  know  the  circum- 
stances, perhaps  purchased  the  brighter  goods,  thinking  that  the 
quality  will  compare  favorably  with  the  color.  Now  this  is  unfair 
to  the  other  man,  and  he  is  discouraged  in  his  efforts  to  manufacture 
pure  goods  simply  because  he  has  no  protection.  In  order  to  get 
the  very  best  goods  it  is  necessary  to  protect  the  packers  against 
every  imitation ;  then  the  inferior  goods  will  show  by  their  color  that 
they  have  not  been  made  from  strictly  fresh  stock.  The  question 
then  arises,  "What  shall  be  done  with  our  surplus  material  which 
may  accumulate,  despite  our  best  efi^orts  to  take  care  of  it  as  fast 
as  it  comes  in?"  There  should  be  arrangements  made  to  put  on 
extra  help  for  such  contingencies,  or  if  this  is  impossible,  the  surplus 
stock  should  be  canned  in  large  size  packages,  such  as  five  or  eight 
gallon  tin  cans,  and  then  sterilized  in  boiling  water;  this  applies 
nicely  to  tomato  pulp  and  if  it  be  put  away  in  this  manner,  it  wnll 
open  up  nearly  as  fresh  and  bright  as  when  first  canned.  Fruits 
contracted  for  preserving  should  be  made  up  into  finished  goods  at 
once,  and  if  properly  handled,  will  need  no  color  to  make  the  finished 
goods  look  well.  There  is  always  enough  natural  color  in  fruits 
to  give  a  good  appearance  to  jams,  jellies  and  preserves,  and  It  is 
pretty  certain  that  such  products  when  colored,  are  either  adulter- 
ated, or  the}^  are  prepared  from  stock  which  has  been  stored  away 
in  packages  which  have  discolored  the  contents.  Now  if  all  this  be 
true,  is  it  not  fair  that  the  packer  who  prepares  for  the  manufacture 
of  his  good  directly  from  fresh  stock  and  who  employs  the  necessary 
labor  and  invests  his  money  at  once  should  have  protection?  If 
anyone  stops  to  think  of  the  result  of  measures  to  protect  first-class 
goods,  he  can  readily  see  that  there  will  be  an  incentive  to  pack  only 
first-class  goods.  One  unit  of  inferior  goods  is  much  more  diffi- 
cult to  force  into  consumption  than  ten  units  of  first-class  goods. 
If  every  packer  will  elevate  his  standard  to  the  very  best,  there  will 
be  ten  times  the  amount  consumed.  The  great  mass  of  the  people 
use  only  sparingly  of  manufactured  canned  goods,  preserves,  jellies 


ARTIFICIAL  SWEETENERS  AND  ADULTERANTS.  305 

and  food  products  in  general,  but  let  them  feel  confident  that  they 
are  getting  just  as  good,  or  perhaps  better  goods,  than  they  prepare 
at  home,  and  the  demand  for  all  kinds  of  food  products  will  be  won- 
derfully increased.  For  a  time  perhaps  this  will  be  difficult  and  ex- 
pensive for  some  packers  who  are  not  prepared  to  pack  all  of  their 
daily  receipts  of  raw  material  into  finished  goods  at  once,  but  it  will 
probably  have  to  be  done  to  comply  with  Pure  Food  Laws.  To  do 
this  perliaps  it  may  be  necessary  to  contract  for  less  produce,  or  it 
will  be  wise  in  any  event  to  prepare  for  storing  raw  material  parti- 
ally finished  in  large  size  tin  cans  which  may  be  sterilized. 

Some  of  the  goods  imported  into  the  United  States  are  very 
highly  colored,  so  much  so  that  they  appear  unnatural,  and  the  De- 
partment of  Agriculture  has  taken  steps  to  stop  the  sale  of  such 
goods.  Much  of  the  blame  for  coloring  our  own  goods  is  due  to 
the  imported  goods;  our  manufacturers  have  been  trying  to  imi- 
tate them  because  there  seemed  to  be  a  popular  belief  that  such 
goods  were  better  than  our  own. 

This  impression,  no  doubt,  was  made  by  the  beautiful  colors 
worked  in  by  the  French  artists.  There  are  no  artificial  colors  so 
delicate  and  beautiful  as  those  painted  by  nature  and  the  American 
people  are  learning  how  to  detect  the  difference.  As  a  matter  of 
fact,  let  me  say  that  there  are  very  few  brands  of  imported  goods 
that  can  compare  in  any  way  with  those  of  some  of  our  best  home 
manufacturers.  Our  goods  are  not  colored  and  perhaps  not  as 
uniform  in  sizes  as  the  imported,  but  for  flavor  and  natural  color 
the}^  far  surpass  those  sold  as  fancy  imported  goods.  This  is  true 
of  the  products  of  many  other  industries  and  I  would  not  be  sur- 
prised that  our  foreign  friends  should  soon  begin  to  take  lessons 
from  our  manufacturers,  indeed  they  are  doing  so  to  some  extent 
now. 

The  hostile  attitude  of  our  Food  Commissioners  against  the 
employment  of  colors  in  foodstuff  has  raised  quite  a  storm  among 
some  manufacturers,  but  if  we  reason  the  matter,  we  must  admit 
that  an  anti-color  crusade  is  bound  to  correct  many  existing  evils 
and  will  in  the  end  be  the  means  of  elevating  the  standard  of  manu- 
factured foods. 

The  profits  on  first-class  goods  are  proportionately  greater  than 
on  cheap  goods,  and  as  much  money  may  be  realized  on  a  smaller 
pack  of  first-class  goods  as  on  a  larger  pack  of  cheap  goods,  and  the 
general  satisfaction  which  such  goods  give  will  make  business  a 
pleasure.  The  packer  who  is  conscious  of  the  fact  that  his  goods 
are  pure  and  wholesome,  prepared  from  selected  raw  material  in 
the  best  possible  manner  knows  that  each  package  will  make  for 
him  a  friend  of  every  consumer,  and  that  means  increased  demand 
for  his  goods  and  a  reputation  for  quality. 


306  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

Some  of  the  raw  materials  used  by  our  packers  may  be  colored 
and  adulterated  and  we  will  give  the  outlines  for  making  analyses 
to  determine  the  presence  of  adulterants.  For  the  complete  study  of 
dyes  and  colors  our  readers  are  referred  to  such  works  as  ''Schultz 
and  Juliuson  Organic  Coloring"  and  "Allen's  Commercial  Organic 
Analysis,"  but  in  a  work  of  this  nature  we  can  only  mention  some 
of  the  most  important  methods  of  color  analyses. 

ARTIFICIAL  COLORS. 

ANAIvYSES   BY   OI^FlCIAIv    METHODS. 

The  separation  and  identification  of  artificial  colors  in  foods 
and  raw  material,  which  is  used  to  make  up  a  finished  food  product, 
is  rather  difficult  in  some  cases,  because  the  quantity  employed  is 
usually  small,  and  becomes  more  or  less  mixed  with  the  natural 
colors.  In  order  to  i-dentify  artificial  colors,  they  must  be  separated 
in  a  pure  state  and  then  tested. 

Coal  tar  dyes  are  identified  by  the  double  dyeing  method,  and 
there  need  be  no  fear  of  mistaking  thern,  if  due  care  is  exercised. 
The  extraction  of  colors  simply  by  the  amyl  alcohol  method,  does 
not  signify  that  those  colors  are  of  coal  tar  origin,  since  many  of 
the  natural  fruit  colors  may  be  thus  extracted,  and  it  is  possible  to 
dye  wool  permanently  with  some  of  them. 

Coal  tar  dyes  are  poisonous,  from  the  fact  that  they  become 
contaminated  with  such  metals  as  zinc,  tin,  lead  and  arsenic,  the 
last  being  present  in  the  sulphuric  acid,  which  is  usually  employed  in 
the  manufacture  of  the  dyes.  Some  of  these  dyes  contain  metals, 
such  as  malachite  green,  which  is  a  double  chlorid  of  zinc,  in  com- 
bination with  the  organic  group.  Many  so-called  vegetable  colors 
are  sold  as  lakes  of  tin  or  alum.  Some  colors  contain  picric  acid, 
and  naphahol  yellow,  and  these  are  known  poisons. 

Combinations  of  dyes  are  sometimes  used,  and  are  difficult  to 
determine;  they  are  detected  by  a  system  of  fractional  dyeing,  the 
fabric  taking  the  different  dyes  at  different  rates  of  time. 

DETECTION  O^  COAX,  TAR  DYES  IN  TOMATOES  A.ND  TOMATO  PRODUCTS. 

Extract  the  color  from  dried  pulp  with  ordinary  alcohol  and 
acidify  with  hydrochloric  acid  and  filter.  Eosin,  which  is  most 
commonly  used,  gives  a  fluorescent  filtrate.  Dilute  the  filtrate  with 
water,  extract  with  amyl  alcohol,  and  dye.  Cochineal,  if  present 
in  the  form  of  a  lake,  will  require  strong  hydrochloric  acid  to  de- 
compose it.  Separate  the  amyl  alcohol,  and  wash  until  neutral. 
Then  divide  into  two  portions,  to  the  first  add  drop  by  drop,  a  very^ 
dilute  solution  of  uranium  acetate,  and  shake  thoroughly  each  time.. 


ARTIFICIAL  SWEETENERS  AND  ADULTERANTS.  307 

The  presence  of  cochineal  is  indicated  by  a  characteristic  emerald 
green  color.  To  the  second  portion,  add  a  drop  or  so  of  ammonia, 
and  the  presence  of  cochineal  is  indicated  by  a  violet  color. 

DETECTION  01^  ARTll^ICIAL  COLORS  IN  PEAS,  BEANS,  GHERKINS, 
ASPARAGUS,  ETC. 

Copper  salts  are  often  used  to  give  color  to  these  vegetables, 
and  sometimes  zinc  is  also  employed.  Reduce  15  to  20  grams  of  the 
suspected  sample  to  an  ash,  transfer  the  ash  to  a  beaker,  and  treat 
with  nitric  acid;  filter,  make  alkaline  with  ammonia,  and  if  a  pre- 
cipitate forms,  filter  again.  A  blue  color  indicates  the  presence  of 
copper.  To  confirm  this  test,  acidify  the  filtrate  with  acetic  acid, 
add  potassium  ferro-cyanide.  Red  coloration  or  precipitate  indi- 
cates the  presence  of  copper,  and  verifies  the  first  test. 

DETECTION  OE  TUMERIC  IN  VARIOUS  PRODUCTS. 

Extract  the  color  from  suspected  sample  with  alcohol.  Dip  a 
piece  of  filter  paper  into  this  tincture  and  dry  at  212°  F.,  after 
which  moisten  with  weak  solution  of  boric  acid,  to  which  a  few 
drops  of  hydrochloric  acid  has  previously  been  added.  Dry  again, 
and  a  cherry  red  color  will  indicate  the  presence  of  tumeric.  This 
color  is  characteristic  and  may  be  learned  by  conducting  a  test  on  a 
known  tumeric  colored  sample. 

DETECTION  OE  COAL  TAR  DYES  IN   JELLIES,   JAMS,   PRESERVES,   ETC. 
METHOD  NO.    I.       (SOSTEGNI  AND  CARPENTiERI.) 

From  10  to  20  grains  of  the  sample  are  dissolved  in  100  c.  c. 
of  water,  filtered  if  necessary,  acidified  with  2  to  4  c.  c.  of  10  per 
cent  solution  of  hydrochloric  acid,  and  a  piece  of  woolen  cloth, 
which  has  been  washed  in  a  very  dilute  solution  of  boiling  potas- 
sium hydroxid  and  then  washed  in  water,  is  immersed  in  it  and 
boiled  for  five  to  ten  minutes.  The  cloth  is  removed,  thoroughly 
washed  in  water,  and  boiled  with  a  very  dilute  hydrochloric  acid 
solution.  Then  after  washing  out  the  acid,  the  color  is  dissolved  in 
a  solution  of  ammonia  hydroxid  (i  to  50).  With  some  of  the 
dyes  the  solution  takes  place  quite  readily,  while  with  others  it  is 
necessary  to  boil  some  time.  The  wool  is  taken  out,  a  slight  excess 
of  hydrochloric  acid  is  added  to  the  solution,  another  piece  of  wool 
is  immersed  and  again  boiled.  With  natural  vegetable  coloring 
matter  this  second  dyeing  gives  practically  no  color,  so  there  is  no 
danger  of  mistaking  vegetable  colors  for  coal  tar  colors.  It  is  abso- 
lutely necessary  that  the  second  dyeing  shotdd  he  done,  as  some  coal 
tar  dyes  will  produce  a  dirty  orange  in  the  first  acid  bath,  which 
might  easily  be  mistaken  for  a  vegetable  color,  but  on  solution  in 


308  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

alkaline  bath,  the  second  acid  bath  will  produce  a  bright  pink  color, 
indicating  that  the  dye  was  of  coal  tar  origin. 

METHOD    NO.    2.        (aRATA.) 

This  method  has  particular  value  for  the  detection  of  coal  tar 
colors  in  fruit  products. 

From  20  to  30  grams  of  the  sample  dissolved  in  100  c.  c.  of 
water,  are  boiled  for  ten  minutes  with  10  c.  c.  of  a  10  per  cent  so- 
lution of  potassium  bi-sulphate,  and  a  piece  of  white  wool  or  woolen 
cloth,  which  has  been  previously  boiled  in  a  very  dilute  solution  of 
sodium  hydroxid  and  thoroughly  washed  in  water  is  boiled  in  the 
solution.  After  removal  from  the  solution,  the  wool  is  washed  in 
boiling  water,  and  dried  between  sheets  of  filter  paper.  If  the  col- 
oring matter  is  a  natural  fruit  color,  the  wool  will  either  be  un- 
colored,  or  will  take  on  a  faint  pink,  or  brown,  which  is  changed  to 
green  or  yellow  by  ammonia,  and  not  restored  by  washing. 

In  addition  to  this,  it  is  advisable  in  all  cases  to  dissolve  out  the 
coloring  matter  with  ammonia,  as  in  the  first  method,  and  dye  again. 

An  advantage  in  the  second  dyeing  is,  that  if  a  large  piece  of 
woolen  cloth  be  used  in  the  first  dyeing,  and  a  small  piece  in  the  sec- 
ond dyeing,  small  amounts  of  coloring  matter  may  be  brought  out 
much  more  decidedly  in  the  second  dyeing,  where  practically  all  of 
the  vegetable  coloring  matter  has  been  excluded.  For  the  identi- 
fication of  the  various  coal  tar  dyes,  the  reader  is  advised  to  consult 
special  works  on  dyeing. 

DETECTION  OE  COAL  TAR  DYES  BY  EXTRACTION  W'lTH  SOLVENTS. 
METHOD  NO.  3.      (method  USED  IN  PARIS  MUNICIPAL  LABORATORY.) 

The  acid  colors  (sulphu-fuchsin,  azo  derivatives  and  phythal- 
eins).,  are  not  precipitated  by  tannin  and  are  insoluble  or  only 
slightly  soluble  in  acetic  acid  or  amyl  alcohol. 

The  basic  colors  (fuschsin,  safranin,  etc.)  are  precipitated  by 
tannin,  and  are  readily  soluble  in  acetic  ether  and  amyl  alcohol. 

No.  I.  To  50  c.  c.  of  suspected  fruit  liquid,  add  ammonium 
hydroxid  in  slight  excess;  then  add  15  c.  c.  of  amyl  alcohol,  shake 
and  allow  to  stand. 

(a)  If  the  alcohol  be  colored  red  or  violet,  decant,  wash,  filter, 
evaporate  to  dryness  in  presence  of  a  piece  of  wool,  and  test  the 
dyed  wool  with  sulphuric  acid. 

(b)  If  the  alcohol  be  not  colored,  separate  and  add  acetic  acid. 
If  the  alcohol  becomes  colored  the  presence  of  basic  aniline  color  is 
indicated. 

(c)  If  the  amyl  alcohol  be  uncolored,  both  before  and  after 
the  addition  of  acetic  acid,  no  basic  coal  tar  color  is  present. 


ARTIFICIAL  SWEETENERS  AND  ADULTERANTS.  309 

No.  2.  Add  an  excess  of  calcined  magnesia,  and  then  a  20 
per  cent  solution  of  mercuric  acetate,  and  bring  to  a  boil.  A  color- 
ation before  or  after  addition  of  acetic  acid  indicates  the  presence 
of  coal  tar  dyes,  particularly  acid  dyes. 

No.  3.  Extract  the  solution  with  acetic  ether  made  alkaline  by 
barium  hydroxid.     This  dissolves  basic  colors. 

In  any  case  the  colors  must  be  fixed  on  wool,  for  many  of  the 
fruit  colors  are  extracted,  and  will  give  reactions  with  sulphuric 
acid,  which  might  possibly  be  mistaken  for  coal  tar  dyes. 

The  double  dyeing  method  will  indicate  clearly  the  difference 
between  the  natural  vegetable  or  fruit  colors  and  those  of  coal  tar 


DETECTION  OE  CARAMEL. 

Syrups,  vinegars,  sauces,  vanilla  extract  and  various  other  pro- 
ducts are  colored  with  caramel,  in  many  cases  to  give  the  impression 
that  the  color  is  due  to  valued  properties. 

Ten  c.  c.  of  the  solution  to  be  tested  are  put  into  a  high,  narrow 
glass  with  perpendicular  sides,  as,  for  example,  a  small  bottle;  add 
from  30  to  50  c.  c.  of  paraldehyde,  depending  on  the  intensity  of 
the  coloring,  and  enough  absolute  alcohol  to  cause  complete  mix- 
ing of  the  solutions.  In  the  presence  of  caramel,  a  brownish  yellow 
to  dark  brown  precipitate  will  collect  in  the  bottom  of  the  glass. 
Decant  the  liquor,  wash  once  with  absolute  alcohol,  dissolve  in  small 
amount  of  hot  w^ater  and  filter.  The  color  of  this  will  give  some 
idea  of  the  quantity  present. 

Concentration  by  evaporation  on  steam  bath  is  not  allowable, 
since  caramel  will  be  formed.  Any  concentration  must  be  done 
over  sulphuric  acid  or  at  diminished  pressure. 

In  order  to  further  identify  the  color,  it  is' poured  into  a  fresh- 
ly prepared  solution  of  phenylhydrazin  (2  parts  phenylhydrazin- 
hydrochlorid,  3  parts  sodium  acetate  and  20  parts  water).  The 
presence  of  a  considerable  quantity  of  caramel  gives  a  dark-brown 
precipitate  in  the  cold  which  is  hastened  by  slightly  heating.  Small 
amounts  require  a  longer  time  for  precipitation. 

DETECTION    OE   STARCH. 

The  packer  often  purchases  various  raw  materials  which  he 
uses  in  the  manufacture  of  specialties.  Sometimes  a  good  body  is 
given  to  certain  substances  by  the  addition  of  starch.  This,  of 
course,  deceives  the  packer,  and  his  finished  product  is  liable  to  be 
condemned  because  he  did  not  know  of  the  existence  of  starch  in 
his  goods.  The  writer  has  received  (and  tested  considerable) 
cream  which  has  been  thickened  in  this  manner. 


310  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

Mustards  are  often  thickened  with  wheat  flour,  and  jelhes  are 
thus  adulterated.  There  may  be  certain  amounts  of  starch  naturally 
in  some  of  these  substances,  but  a  quantitative  test  will  enable  the 
packer  to  judge  of  this  by  analyzing  a  sample  of  known  purity. 
Some  unripe  fruits  will  show  the  presence  of  considerable  starch, 
but  later  this  is  converted  into  sugar  during  the  ripening.  For 
this  reason  good  judgment  is  necessary  in  making  tests  for  starch 
in  products  made  from  certain  fruits.  If  the  suspected  sample  has 
much  color,  this  may  be  destroyed  with  sulphuric  acid  and  perman- 
ganate of  potassium.  First  heat  the  sample  to  nearly  212°  F.  and 
add  a  small  quantity  of  sulphuric  acid  followed  by  permanganate  of 
potassium  until  the  color  is  destroyed.  A  few  drops  of  tincture  of 
iodin  will  give  a  blue  color  indicating  the  presence  of  starch. 

There  are  various  other  raw  materials  used  in  special  food 
formulas  which  are  frequently  adulterated,  and  it  is  necessary  that 
the  packers  should  know  how  to  determine  the  presence  of  adulter- 
ants. 

Our  food  manufacturers  desire  a  better  standard  than  ever  be- 
fore, and  it  is  only  a  question  of  time  when  the  employment  of  arti- 
ficial colors  and  adulterants  of  all  kinds  will  be  looked  upon  with  dis- 
favor. Our  efforts  to  bring  out  these  points  clearly  may  seem  a 
little  too  far  advanced,  but  undoubtedly  there  has  been  too  much 
of  this  done,  and,  we  believe,  unnecessarily.  Let  us  have  our  ideal 
strictly  pure,  wholesome,  unadulterated  food  products,  and  earnestly 
strive  to  establish  that  standard. 

Fruits  and  vegetables,  jellies,  preserves  and  other  products 
whose  color  is  easily  affected,  may  now  be  put  up  in  tin  cans,  coat- 
ed or  enameled  on  the  inside,  with  a  substance  which  is  impervious 
to  acids  and  is  baked  on  the  tin  in  such  a  manner,  that  a  heavy  steri- 
lizing process  does  not  remove  it. 

This  inside  coating  is  done  by  two  firms.  The  Sanitary  Can 
Company,  of  Fairport,  N.  Y.,  and  The  National  Canning  &  Manu- 
facturing Company,  of  Baltimore,  Md.  By  using  these  cans,  the 
problem  of  how  to  preserve  the  natural  color  of  food  products  is 
solved. 


THE  CANNING  INDUSTRY.  311 

CHAPTER  XI. 
The  Canning  Industry 

A  Short  History.     Location  and  Equipment  of  a  Canning  Factory. 
What  to  Can.     Selection  of  Raw  Material. 


A  SHORT   HISTORY,   PAST,   PRESENT  AND   EUTURE. 

In  the  year  1810  N.  Appert,  a  Frenchman,  published  his  work 
on  canning.  He  had  received  a  prize  of  12,000  francs  from  the 
French  government  the  year  previous.  About  the  same  time  Peter 
Durrand  obtained  a  patent  in  England  for  a  process  of  preserving 
fruit,  meats  and  vegetables  in  tin  cans  are  the  patents  granted  to  a 
Frenchman  by  name  of  Pierre  Antoine  Angilbert,  in  1823.  In 
America,  the  canning  industry  was  started  in  Maine,  by  Isaac  Wins- 
low,  in  1839,  and  about  the  same  time  Edward  Wright  began  to 
pack  oysters  in  Baltimore. 

Winslow  began  packing  corn,  which  was  very  fine  in  quality, 
and  he  succeeded  in  preserving  a  great  deal  by  simply  processing 
the  cans  for  several  hours  in  boiling  water.  His  first  experiments 
were  made  with  corn  on  the  cob,  but  he  soon  discovered  that  the 
sweetness  of  the  kernels  was  absorbed  by  the  cob,  so  he  gave  up 
the  idea  and  cut  the  corn  by  means  of  a  curved  and  gauged  knife. 

There  are  some  records  which  seem  to  indicate  that  William 
Underwood  began  to  pack  certain  foods  in  hermetically  sealed  pack- 
ages, in  Boston,  Mass.,  about  the  same  time,  or  prior  to  the  estab- 
lishment of  corn  packing  in  Maine.  The  records  available  prove 
that  William  Underwood  did  pack  preserves  and  table  condiments  in 
glass,  as  early  as  1828,  and  in  1836  he  was  packing  tomatoes  in 
glass,  but  there  are  probably  no  earlier  records  of  goods  having 
been  packed  in  tin  cans,  than  those  of  Isaac  Winslow. 

In  i860,  the  canning  of  corn,  tomatoes,  and  fruits,  was  started 
by  my  father,  Thomas  Duckwall,  near  Cincinnati,  Ohio.  There  is 
no  record  of  any  canning  in  the  Middle  States  prior  to  that  time, 
and  thus  Thomas  Duckwall  is  recognized  as  the  pioneer  of  the  in- 
dustry in  that  section. 

Tin  cans  were  difficult  to  make  and  owing  to  the  crude  appara- 
tus for  cutting  tops  and  bottoms,  the  process  was  slow.  A  weight 
was  pulled  up  to  the  ceiling  and  allowed  to  drop  upon  a  sheet  of  tin ; 
a  die  was  cast  on  the  under  side  of  the  weight,  and  the  opposite  die 
was  cast  in  a  piece  of  metal  below,  so  that  the  forming  of  tops  and 


312  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

bottoms  depended  on  the  weight  being  properly  guided.  To  make 
this  operation  as  accurate  as  possible,  the  weight  had  two  upright 
grooved  guides,  the  same  as  those  used  to  guide  the  weight  in  pile 
driving.     My  father  made  his  first  cans  in  this  manner. 

Canning  of  fruits  and  vegetables  began  in  California  about 
1 86 1 -2,  and  to  Francis  Cutting  belongs  the  honor  of  having  been 
the  first  man  to  make  and  fill  tin  cans,  although  to  his  foreman, 
Alexander  Young,  belongs  the  credit  of  actually  producing  the  re- 
sults, from  his  practical  knowledge.  California  proved  to  be  a 
splendid  country  for  growing  all  kinds  of  fruits  and  vegetables,  so 
that  canning  factories  sprang  up  all  over  the  state,  and  the  present 
output  is  enormous.  The  quality  of  goods  manufactured  is  high, 
and  the  canning  business  occupies  a  very  prominent  place  in  the 
list  of  California  industries. 

The  growth  of  the  canning  industry  was  rapid,  after  having 
been  thus  established  in  various  parts  of  the  country.  New  methods 
for  making  cans,  improved  machinery  and  skilled  help  quickly  de- 
veloped, and  the  increasing  demand  for  the  goods,  gave  the  neces- 
sary impetus.  In  the  eighties  the  growth  of  the  industry  was  phen- 
omenal, and  new  canneries  sprang  up  like  mushrooms  all  over  the 
country,  and  the  unskilled  vied  with  the  older-established  packers, 
in  the  quantities  of  canned  goods  they  could  put  up.  The  result 
was  that  a  great  deal  of  cheap,  unwholesome  goods  soon  flooded 
the  market,  and  people  became  disgusted  to  the  extent  that  they 
began  putting  up  a  large  per  cent  of  preserved  and  canned  goods  at 
home. 

There  were  several  causes  for  this  reaction;  the  machinery 
men  and  promoters  pushed  their  plans  too  fast,  and  unskilled  men 
took  charge  of  the  canneries,  and  were  soon  packing  all  kinds  of 
fruits  and  vegetable,  and  much  inferior  stuff  resulted  from  inexperi- 
ence. The  wholesale  grocers  took  a  hand  and  began  to  squeeze  the 
price  down,  at  the  same  time  requiring  private  labels  which  did  not 
give  the  packer's  name.  Under  such  labels  some  very  poor  goods 
were  manufactured,  simply  because  the  price  was  too  low,  and  the 
fictitious  label  relieved  the  packer  of  the  responsibility  for  the 
quality. 

The  result  of  low  prices  and  loss  of  trade  drove  many  canners 
out  of  the  business,  and  the  old  established  packers  began  with  a 
determination  to  make  ^^ quality"  their  aim. 

They  began  to  give  close  attention  to  the  selection  of  raw 
produce,  forcing  the  farmers  to  furnish  prime  material,  and  to-day 
this  is  one  of  the  most  important  factors  in  the  production  of  first- 
class  goods.  Experienced  men  are  in  demand  to  supervise  the 
work,  and  these  are  men  who  have  not  only  a  practical  but  also  a 
scientific  knowledge  of  canning  and  preserving.     There  is  now  a 


THE  CANNING  INDUSTRY.  313 

much  better  class  of  canned  food  products  offered  to  the  trade  than 
ever  before,  but  for  some  time  there  have  been  flourishing  numerous 
concerns  who  have  been  packing  a  very  poor  quaHty  of  goods,  es- 
pecially in  the  line  of  specialities.  Some  of  these  goods  are  so 
skillfully  colored  and  preserved  with  antiseptics  as  to  deceive  the  un- 
suspecting consumer.  Thus  we  have  the  two  extremes  in  manu- 
factured food  products,  one  representing  the  very  best,  purest  and 
most  wholesome,  that  modern  knowledge  and  skill  are  able  to  pro- 
duce ;  the  other  representing  imitations  of  the  better  goods,  and 
these  are  highly  colored,  adulterated  and  preserved  by  means  of 
chemicals. 

There  has  never  been  a  time  when  strictly  first-class  food  pro- 
ducts were  manufactured  in  excess  of  their  demand  by  the  trade. 
On  the  other  hand  the  market  has  been  repeatedly  overloaded  and 
injured  by  the  cheap  goods  we  have  mentioned.  The  people,  and 
particularly  the  masses,  as  a  rule  purchase  the  cheap  goods,  and 
the  quality  is  often  so  poor  as  to  disgust  them,  so  the  whole  industry 
suffers  much  when  the  reaction  comes.  The  masses  are  good  ad- 
vertisers of  poor  and  also  good  food  products  and  their  condemna- 
tion or  approval  has  power. 

//  the  people  of  this  country  had  implicit  confidence  in  ell  manu- 
factured food  products,  and  all  zvere  strictly  first-class,  the  maxi- 
mum capacity  of  all  the  fc dories  would  he  insufficient  to  supply 
the  demand.  If  you  take  the  yearly  output  of  these  factories,  and 
figure  out  a  pro  rata  for  each  person  the  result  w^ill  convince  you 
that  there  are  wonderful  possibilities  for  the  food  industry.  This 
felicitous  state  of  affairs  can  never  be  realized  until  all  manufac- 
turers enjoy  the  fullest  confidence  of  the  masses. 

Having-  briefly  outlined  the  history  of  canning  and  preserving 
from  its  beginning  and  having  pried  into  the  future,  we  may  take 
a  broad  view  of  the  present  crusade  against  impure  and  low  grade 
foods :  it  cannot  be  doubted  that  much  good  will  result  for  the  man- 
ufacturers. To  be  sure,  if  the  laws  are  made  excessivelv  strict, 
some  packers  may  be  compelled  to  turn  their  attention  to  other  lines 
of  business,  but  those  wdio  comply  with  the  conditions  set  forth  in 
a  strict  national  law  will  enjoy  an  unparalleled  future  demand  for 
their  goods,  because  home  canning  and  preserving  will  decrease  in 
proportion  to  the  decrease  of  impure,  unwholesome  and  adulterated 
goods. 

How  may  this  be  done?  Several  ideas  suggest  themselves: 
First,  there  must  be  protection  by  a  national  law;  second,  strict 
compliance  with  the  provisions  of  that  law ;  third,  a  resolution  to 
pack  only  the  finest  quality  in  cans  or  glass.  To  do  this,  it  may 
be  necessary  to  cut  down  the  quantity  of  goods  manufactured,  in 
order  that  actual  capacity  may  not  be  exceeded.     The  quality  of 


314  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

such  goods  will  no  doubt  bring  as  large,  perhaps  larger,  returns  than 
the  goods  of  poorer  quality.  It  may  be  necessary  to  employ  more 
skillful  men;  it  may  be  necessary  to  lay  aside  a  machine  which 
crushes  the  fruits  or  vegetables  according  to  present  methods;  it 
may  be  necessary  to  add  improved  machiner}^  in  one  place  and  to 
employ  hand  work  in  another ;  it  may  be  necessary  to  limit  the  sell- 
ing territory;  but  whatever  it  may  require,  the  end  will  justify  the 
means,  profits  will  be  larger,  and,  while  capital  may  be  limited,  a 
good  reputation  and  a  growing  trade  will  generally  be  an  inviting 
field  for  outside  capital,  if  needed. 

LOCATION   AND   EQUIPMENT   OE  A   CANNING   FACTORY. 

The  location  of  a  canning  factory  is  important,  and  the  suc- 
cess of  the  business  may  depend  entirely  upon  that,  if  everything  else 
is  all  right.  It  is  not  enough  to  depend  upon  the  ability  to  secure 
plenty  of  fruits,  vegetables,  etc.  There  must  also  be  available  help, 
and  this  is  often  a  difficult  problem  in  small  places.  Glowing  ac- 
counts of  fine  crops  and  offers  of  free  ground  have  led  many  to  es- 
tablish canning  factories  in  various  places,  and  the  after  failures 
were  due  to  the  difficulties  experienced  in  securing  sufficient  and  suit- 
able help  to  take  care  of  the  stock  delivered  by  the  farmers.  Im- 
proved labor-saving  machinery  has  done  much  to  remove  this  diffi- 
cult}^  but  it  is  often  not  an  easy  matter  to  procure  suitable  persons 
to  operate  the  machinery.  Then  again,  certain  machinery  may  save 
labor  yet  may  so  crush  and  bruise  the  stock  that  only  a  poor  quality 
of  goods  may  result.  Even  good  machinery  may  be  so  poorly  op- 
erated as  to  ruin  the  quality  of  the  stock.  Goods  of  fine  quality  can- 
not be  produced  in  a  factory  where  the  stock  is  filled  into  the  cans 
in  a  careless  manner.  Another  important  factor  in  selecting  a  lo- 
cation is  the  shipping  facility.  A  canning  factory  should  be  near 
one  railroad,  and  near  two,  if  possible.  During  the  season  it 
is  often  necessary  to  receive  supplies  promptly,  and  the  shipping 
of  finished  goods  should  be  done  with  as  little  hauling  by  wagons  as 
possible.  Where  two  railroads  are  available  the  rates  are  generally 
lower  and  the  service  much  better  than  where  one  line  has  com- 
plete control.  As  a  rule,  it  is  better  to  locate  the  canning  factory 
as  near  as  possible  to  the  larger  cities  and  towns;  the  difficulties  ex- 
perienced in  obtaining  farm  products  may  be  greater,  but  these  are 
more  than  offset  by  the  advantages  in  securing  good  help  and  ship- 
ping accommodations.  Promoters  of  canning  factories  have  been 
to  blame  in  many  cases  for  the  establishment  of  these  enterprises  in 
so  many  unfavorable  places ;  the  many  idle  factories  we  see  on  coun- 
try cross-roads  are  witnesses  to  the  truth  of  our  statement,  and 
the  proper  location  of  the  canning  factory  must  ever  be  a  matter  of 
prime  importance. 


THE  CANNING  INDUSTRY.  315 

EQUIPMENT    01^    A    CANNING    FACTORY. 

The  proper  equipment  of  the  factory  is  a  most  important  con- 
sideration. A  poor  equipment  or  one  that  is  out  of  date  not  only 
increases  the  cost  of  packing,  but  also  is  a  hindrance  in  the  pro- 
duction of  best  quality.  The  building  itself  should  be  adapted  to 
the  particular  line  of  goods  manufactured  and  the  arrangements  for 
receiving  raw  material  and  the  shipping  should  be  made  in  such  a 
manner  as  to  avoid  any  back  steps.  Whenever  goods  have  to  be 
taken  over  the  same  space  two  or  more  times  the  cost  of  produc- 
tion is  materially  increased.  This  is  usually  the  result  of  imper- 
fections in  building  and  should  be  overcome  by  making  such  addi- 
tions as  may  be  necessary  to  facilitate  the  work.  It  is  no  uncom- 
mon sight  to  see  goods  trucked  up  and  down  elevators  two  or  three 
times  iDcfore  shipment.  A  proper  storage  place  should  be  laid  off 
on  the  same  floor  from  which  the  goods  are  to  be  shipped.  It  costs 
considerable  to  load  and  unload  trucks  and  there  is  always  consider- 
able time  lost  in  waiting  for  elevators. 

Every  canning  factory  should  have  good  boiler  capacity,  so 
that  a  nearly  uniform  steam  pressure  may  be  maintained  without 
overfiring  the  boilers.  The  quality  of  a  large  per  cent  of  food  pro- 
ducts depends  in  part  upon  uniformity  of  steam  pressure.  A  pres- 
sure of  about  90  pounds  gives  splendid  results  generally.  The 
proper  circulation  of  steam  in  the  sterilizing  retorts  is  important  and 
cannot  be  as  uniform  when  the  boiler  pressure  falls  to  40  to  60 
pounds.  There  is  always  more  or  less  condensation  of  steam  at 
the  optimum  pressure,  even  when  the  pipes  are  covered  with  asbes- 
tos; but  there  is  decidedly  too  much  condensation  at  the  low  pres- 
sures mentioned. 

Nearly  all  of  the  old  packers  have  had  considerable  experience 
along  this  line,  and  some  very  severe  cases  of  spoilage  have  been 
traced  directly  to  improper  steam  circulation,  due  to  low  steam  pres- 
sure in  the  boiler.  For  scalding  tomatoes  there  should  be  sufficient 
steam  pressure  to  make  water  boil  vigorously.  This  will  loosen  the 
skin  of  the  tomato  and  will  not  cook  the  fruit.  After  the  proper 
scalding  of  tomatoes,  the  thin  skin  will  peel  Off  easily,  and  the  to- 
mato will  be  cool  inside  and  will  be  firmer,  and  will  hold  its  juice 
much  better  than  when  partially  cooked  during  the  scalding.  Some 
factories  have  considerable  waste  in  the  peeling ;  the  fruit  had  been 
partly  cooked  and  a  layer  of  the  tomato  would  come  off  with  the 
pee] ;  this  is  due  to  poor  steam. 

For  blanching  purposes  there  should  always  be  good  steam 
pressure,  and  for  all  evaporating  work  the  pressure  should  be  high. 
The  making  of  tomato  catsup.  Chili-sauce,  etc.,  requires  sufficient 
steam  pressure  to  insure  perfect  circulation  in  the  jacket  of  the  ket- 


316  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

tie;  this  will   insure  rapid  evaporation   and   ebullition   sufficiently- 
strong  to  avoid  scorching  or  sticking. 

All  goods  which  are  to  be  cooked  with  live  steam  should 
have  high  pressure  to  avoid  as  much  as  possible  the' water  of  con- 
condensation  so  copious  in  steam  of  low  pressure.  The  water  of 
condensation  has  a  peculiar  flat  taste  so  often  observed  in  distilled 
water,  and  this  flavor  is  imparted  to  some  goods,  which  greatly  in- 
jures their  quality. 

To  get  the  best  results  with  steam,  it  is  quite  essential  that  all 
cooking  should  be  done  as  near  to  the  boiler  room  as  possible.  The 
nearer  the  cooking  is  to  the  boiler  the  less  will  be  the  water  of  con- 
densation, and  the  better  will  be  the  circulation.  If  coal  be  used  as 
fuel  for  boiler,  the  automatic  feed  is  to  be  commended  as  a  clean  and 
labor-saving  apparatus ;  it  cannot  always  be  used  to  advantage,  how- 
ever, because  it  requires  a  coal  storage,  one  floor  above  the  boiler 
room. 

For  power  and  lighting,  the  electric  system  is  better  and  more 
economical  than  belting.  The  power  may  be  carried  to  all  parts  of 
the  building  through  small,  well  insulated  wires,  which  may  oper- 
ate motors  at  the  points  most  advantageous,  and  when  not  in  use 
may  be  shut  off,  thus  saving  considerable  energy.  This  system  is 
especially  attractive  where  the  business  is  large  and  conducted  on 
several  floors  or  in  different  buildings. 

The  various  products  which  are  to  be  canned,  preserved  or 
bottled,  generally  require  machinery  specially  constructed  to  do  the 
work,  and  when  it  is  known  just  what  kinds  of  goods  are  to  be  pre- 
pared, it  is  a  matter  of  judgment  to  determine  what  machines  are 
the  best  for  the  purpose.  There  are  machinery  manufacturers  who 
have  special  lines  for  the  canning  of  all  regular  products,  such  as 
corn,  peas  and  tomatoes,  and  the  catalogues  describe  them  fully. 
Some  modern  machinery,  however,  is  built  more  for  speed  than 
quality,  and  it  is  impossible  to  produce  strictly  first-class  goods. 
Special  care  must  be  taken  to  adopt  no  filling  machine  which  in  any 
way  crushes  the  product  to  be  canned.  vSome  of  the  tomato  fillers 
on  the  market  crush  and  mash  the  fruit  so  badly  that  the  contents 
afterwards  appear  more  like  slop  than  standard.  It  would  be  diffi- 
cult to  do  all  of  this  work  by  hand,  nor  is  it  necessary,  because  the 
consumer  does  not  look  for  canned  tomatoes  firm  and  whole,  unless 
he  calls  for  such  goods,  which  are  classed  as  "fancy."  It  has  been 
decided  that  the  best  tomato-fillers  do  not  crush  the  fruit  as  much  as 
the  ordinary  careless  hand-filler.  All  fancy  goods  are  filled  by 
hand,  however,  and  only  uniform,  selected  tomatoes  are  used. 

There  are  two  systems  for  hermetically  sealing  tin  cans.  One 
used  in  European  countries,  and  also  in  this  country,  seals  the  can 


THE  CANNING  INDUSTRY.  317 

by  crimping  the  top  on  to  the  flanged  body,  the  seaHng  being  made 
secnre  by  a  patented  cement  resembhng  rnbber.  This  method  has 
many  advantages  over  the  ordinary  method  of  soldering;  fruits  and 
vegetables  may  be  filled  into  the  cans  whole ;  there  is  no  danger  of 
getting  any  soldering  solution  inside  the  cans;  there  is  absolutely 
no  danger  from  lead  poisoning,  which  is  perhaps  wrongfully  blamed 
on  the  soldering  system,  although  cans  which  are  sealed  with  solder 
do  not  find  favor  in  several  foreign  markets  for  this  alleged  rea- 
son. 

With  due  care  I  believe  that  the  wonderfully  improved  auto- 
matic capping  machines,  such  as  are  used  all  over  this  country,  will 
seal  the  cans  perfectly  without  any  danger  of  lead  poison  affect- 
ing the  contents.  There  are  times,  however,  when  these  machines 
get  out  of  order  and  do  not  work  smoothly,  and  great  care  must  be 
exercised  to  avoid  contaminations  from  soldering  solution  and  small 
drops  of  solder.  The  latter  often  get  into  the  cans  from  the  ''tip- 
ping" or  "dotting,"  which  must  not  be  done  until  the  caps  are  cooled 
sufficiently.  From  my  experience,  it  is  a  wise  plan  to  chill  the  cans 
with  air  from  the  blower  or  to  keep  the  tippers  at  least  fifteen  feet 
from  the  capping  machine. 

The  Calcium  System  is  manufactured  by  The  Sprague  Canning 
Machinery  Company,  of  Chicago. 

For  processing,  some  prefer  the  regular  steam  retorts,  some 
use  the  calcium  and  oil  systems,  and  for  open  bath  sterilization  sim- 
ply the  open  retorts  filled  to  a  certain  height  with  boiling  water,  or 
the  continuous  system  where  the  cans  travel  through  water.  These 
systems  are  all  good  for  certain  lines,  but  the  continuous  calcium 
system  offers  some  advantages,  from  the  fact  that  a  given  tem.pera- 
ture  may  be  maintained  without  the  constant  escape  of  steam.  The 
small  expense  of  keeping  the  temperature  at  a  given  point  is  one 
of  the  chief  attractions  of  this  system;  this  may  be  done  with  the 
exhaust  steam  from  the  engine  or  with  only  a  small  supply  of  steam 
direct  from  the  boiler.  After  the  first  cost  is  paid  the  running  ex- 
pense is  small  and  the  cost  may  be  saved  (on  fuel)  in  a  short  time. 

In  connection  with  the  canning  of  peas  there  are  machines  used 
for  vining  and  hulling  v/hich  must  be  operated  in  such  a  manner 
that  the  shelled  peas  may  be  quickly  separated  and  canned  before 
decomposition  sets  in.  I  do  not  know  of  any  system  where  the 
danger  of  depreciating-  the  quality  is  so  great,  unless  due  care  is 
exercised  in  handling  the  peas  quickly.  The  viners  are  sometimes 
operated  several  miles  away  from  the  factory,  and  the  hulled  peas 
are  put  into  baskets  to  a  depth  of  five  to  eight  inches ;  and  are  then 
hauled  on  wagons  and  piled  up  ahead  of  the  separating  machines. 
Sometimes  several  hours  elapse  before  these  peas  are  blanched  and 
in  that  time  the  bacteria  usually  found  on  the  vines  and  hulls  get  a 
wonderful  start,  producing  bitter  compounds  and  mucilaginous  sub- 


318  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

stances  which  so  often  cause  turbidity  and  ropiness  in  the  liquor  of 
canned  peas. 

The  machines  to  which  we  have  referred  are  wonderful  achieve- 
ments of  skill  and  practical  knowledge,  and  if  properly  operated  give 
better  results  than  hand  work,  but  they  should  always  be  set  up 
quite  near  the  factory  and  should  not  be  operated  faster  than  the 
peas  can  be  handled  in  the  canning  department.  Many  samples 
of  canned  peas,  having  clouded  liquor,  have  been  sent  to  the  Na- 
tional Canners'  Laboratory,  and  the  cause  has  been  frequently  traced 
to  the  improper  method  of  operating  the  vining  machines.  The 
vines  should  be  cut,  hauled  to  the  factory,  and  the  motto  should 
then  be :     ''From  the  vine  to  the  can  in  the  shortest  possible  time.'' 

The  manufacturer  of  special  food  products  requires  special 
machinery,  which  may  have  to  be  built  according  to  the  packer's 
ideas  and  for  the  accomplishment  of  special  requirements.  There 
are  a  great  many  special  food  products  sold  under  trade  names,  and 
the  machinery  for  such  will  be  described  under  the  particular  head- 
ings. One  important  fact  must  ever  be  borne  in  mind,  viz. :  Every 
package  will  reach  a  customer,  and  if  there  are  any  defects  due  to 
carelessness  on  the  part  of  employees  who  operate  the  machines  or 
to  break-downs,  they  should  be  watched  and  the  cans  should  be  in- 
spected at  the  point  nearest  to  the  final  sealing,  and  all  that  are  de- 
fective in  any  way  should  be  taken  out.  Every  can  either  makes  a 
friend  or  an  enemy  of  the  consumer,  and  the  proper  handling  of  the 
equipment  is  therefore  very  important. 

Capacity  of  the  equipment  is  another  important  factor  in  pro- 
ducing goods  of  fine  quality.  There  should  always  be  enough  ma- 
chines to  take  care  of  all  the  raw  material  received  as  rapidly  as  pos- 
sible. It  is  not  wise  to  run  full  with  no  reserve  machines  to  take  up 
the  work  in  case  of  break-downs.  This  point  is  frequently  over- 
looked by  some  packers  and  it  happens  most  frequently  that  the  cap- 
ping machines  are  unable  to  take  care  of  the  cans.  A  reserve  ma- 
chine should  always  be  kept  in  good  running  order,  so  that  any 
breakdown  may  not  delay  the  cans  which  are  waiting  to  be  sealed. 

It  is  not  a  good  plan  to  operate  too  many  automatic  machines 
in  a  single  system.  Automatic  machines  frequently  get  out  of 
order,  or  need  adjustment  of  some  delicate  parts,  and  if  a  number 
are  operated  in  a  single  system,  there  is  too  much  loss  of  time. 

It  is  better  to  operate  some  machines,  from  separate  shafting, 
and  regulate  the  speed  in  such  a  manner  as  to  keep  the  whole  system 
in  running  order. 

Machines  should  never  be  crowded  too  closely.  As  a  rule, 
losses  and  damaged  goods  result  from  overcrowding.  There  should 
be  plenty  of  room  to  operate  them  and  the  most  experienced  people 
placed  in  charge,  to  get  the  best  results. 


THE  CANNING  INDUSTRY.  319 

There  are  many  factories  throughout  the  country  which  are  not 
properly  equipped.  Every  improved  machine  should  be  carefully 
studied,  especially  if  it  has  any  advantage  in  the  speed  and  char- 
acter of  work  turned  out.  Many  packers,  on  the  other  hand,  go  to 
extremes  and  adopt  every  new  machine  put  on  the  market,  whether 
it  offers  any  advantage  or  not,  and  the  expression,  ''I  am  machinery 
poor,"  is  frequently  heard.  It  is  perhaps  a  good  plan  to  take  in,  on 
trial,  any  machine  which  appears  to  offer  some  advantages,  but  if 
there  is  loss  of  time  or  danger  of  injuring  the  quality  of  the  goods 
it  should  not  be  accepted.  Therefore  the  proper  equipment  of  a 
canning  factory  is  a  problem  which  must  be  solved  by  every  packer 
for  himself.  The  chief  points  to  be  observed  are  the  continuous 
arrangement,  to  avoid  retracing ;  selection  of  only  the  best  machines ; 
the  proper  placing  and  operating,  with  due  regard  always  for  speed 
and  improved  quality  of  the  goods  manufactured. 

WHAT  TO  PACK. 

This  is  an  important  consideration ;  'Svhat  to  pack"  claims  the 
attention  before  either  building  or  equipment.  It  is  sometimes  diffi- 
cult to  foretell  just  what  specialties  may  become  a  part  of  the  busi- 
ness after  it  is  established,  but  it  must  be  decided  just  what  will  be 
the  best  line  of  goods  to  be  manufactured.  When  the  conditions 
are  favorable,  peas,  tomatoes  and  corn  are  packed  by  some  houses, 
but  generally  not  more  than  two  of  these  are  packed  in  one  location. 
In  some  locations  the  whole  interest  centers  in  one,  and  then  other 
kinds  of  goods,  such  as  berries,  fruits,  pumpkin  and  a  long  line  of 
specialties,  are  packed  to  keep  the  factory  in  active  operation  and 
give  employment  to  valued  help. 

There  are  certain  sections  of  the  United  States  where  peas, 
tomatoes  or  corn  are  better  in  quality  than  those  grown  anywhere 
else;  thus  the  New  England  states.  New  York  and  a  few  other 
places,  are  noted  for  the  fine,  rich  flavor  of  the  corn  grown  there. 
Michigan,  Wisconsin  and  some  other  places  are  noted  for  the  deli- 
cate, sweet  flavor  of  their  peas.  Delaware,  Maryland  and  Indiana 
are  noted  for  their  excellent  tomatoes,  and  many  other  places  have 
records  for  the  excellency  of  this  valuable  product. 

There  are  certain  localities  where  a  very  excellent  crop  of  any 
of  these  staples  is  raised  occasionally,  and  when  the  report  is  pub- 
lished it  sometimes  proves  a  strong  inducement  for  the  establishment 
of  canning  factories.  There  are  many  places  which  boast  of  their 
canning  factories  and  are  not  able  to  supply  them  with  the  products 
to  keep  them  running. 

There  are  certain  localities  where  the  conditions  seem  favor- 
able for  large  crops  of  peas,  corn,  etc.,  and  in  fact  large  quantities 
are  grown,  but  the  flavor  and  quality  in  general  is  quite  poor  in 
comparison  with  that  of  more  favored  places;  the  peas  are  mealy 


320  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

and  almost  tasteless  perhaps,  or  the  corn  is  tough,  dry  and  not  sweet, 
and  so  it  is  impossible  to  get  a  quality  of  the  canned  article  that 
will  compare  favorably  with  that  of  other  sections. 

It  is  for  this  reason  that  saccharin  has  been  so  generally  used 
by  packers  of  peas  and  corn  in  unfavored  locations.  There  is  no 
question  but  that  a  small  addition  of  granulated  sugar  does  im- 
prove the  quality,  but  the  cost  is  great,  and  so  saccharin  sold  under 
various  trade  names  has  been  used  by  not  a  few  packers. 

In  determining  what  to  pack,  it  is  not  enough  to  have  large 
crops  of  any  particular  fruit  or  vegetable,  but  the  quality  must  also 
be  determined  to  see  how  it  will  compare  with  that  of  well  known 
standards.  All  the  skill  and  knowledge  possible  would  not  raise 
the  standard  up  to  the  very  best,  unless  the  original  quality  was 
good.  How  many  houses  are  trying  to  do  this  very  thing  ?  When 
it  is  certain  that  the  raw  product  is  inferior  in  quality  and  that  no 
amount  of  skill  in  packing  will  ever  bring  the  finished  product  up  to 
the  regular  standard,  it  would  be  wise  to  discontinue  for  the  rea- 
son that  no  reputation  can  be  built  up  on  such  goods,  and  even 
though  a  small  margin  may  possibly  be  realized,  the  reputation  is 
injured  an.d  the  general  effect  on  the  market  is  not  good.  A  loca- 
tion may  be  very  favorable  for  packing  tomatoes,  but  not  for  corn, 
so  it  would  be  better  to  build  up  a  line  of  tomato  specialities  which 
may  be  manufactured  during  the  months  following  the  tomato  sea- 
son, and  not  attempt  to  pack  corn,  even  though  large  crops  may  be 
realized,  if  the  quality  be  not  up  to  that  of  recognized  standards. 

Some  houses  make  a  specialty  of  canning  tomatoes  and  follow 
this  with  the  manufacture  of  tomato  catsup.  Chili-sauce,  etc.,  which 
is  a  splendid  idea  if  the  tomatoes  are  well  suited  for  making  these 
condiments.  It  is  a  fact  worthy  of  notice,  however,  that  only  a  few 
localities  produce  tomatos  fit  for  strictly  first-class  tomato  catsup. 

Much  of  the  piquant  flavor  of  catsup  is  due  to  the  natural  acid-' 
ity  of  the  tomato,  and  such  tomatoes  are  not  as  solid  and  meaty  as 
are  generally  used  for  canning  purposes.  As  a  rule  the  finest  to- 
matoes for  canning  are  solid  and  do  not  contain  too  much  juice. 

Small  fruits  are  not  grown  in  sufficient  quantities  for  canning 
purposes  outside  of  certain  sections,  such  as  the  eastern  and  extreme 
western  coast  states  and  the  fruit  belt  near  the  Great  Lakes,  and  al- 
though other  localities  m.ay  at  times  have  crops  of  berries  and 
peaches,  they  are,  as  a  rule,  inferior  in  size  and  flavor  to  those  grown 
in  the  places  we  have  named.  It  is  possible,  however,  to  have  these 
fruits  shipped  into  less  favored  places,  and  they  may  be  either  can- 
ned or  made  up  into  jellies,  preserves,  butters  and  jams ;  but  the  ex- 
pense of  shipping  is  great  and  the  quality  very  materially  affected, 
therefore,  it  is  advisable  to  pack  such  goods  as  near  as  possible  to  the 
point  where  the  fruits  are  grown.  One  factory  in  California  is 
located  in  the  center  of  its  orchards  and  the  flavor  and  quality  of  the 


THE  CANNING  INDUSTRY.  321 

goods  packed  is  very  fine  and  is  a  credit  not  only  to  the  firm,  but  also 
to  the  whole  industry.     The  fruit  is  packed  as  soon  as  it  is  picked. 

There  is  a  long  list  of  specialties,  some  of  which  may  be  added 
to  a  business  which  will  keep  the  factory  running  between  seasons, 
and  they  are  quite  profitable,  too,  if  the  very  highest  quality  is  main- 
tained. There  are  a  number  of  concerns  which  produce  lines  of 
specialities  to  fill  in  between  seasons,  and  the  quality  of  the  goods  is 
so  poor  that  the  market  is  glutted,  and  the  whole  industry  suffers 
materially. 

Some  of  the  houses  of  which  we  are  speaking  sent  up  into 
Michigan  several  years  ago  and  bought  large  quantities  of  navy 
beans  which  were  moldy  and  blighted  on  account  of  rains  and  un- 
favorable crop  conditions.  These  beans  were  soaked,  boiled  and 
covered  with  a  very  low  grade  of  sauce,  and  No.  3  cans  were  sold 
on  the  market  for  10  cents.  They  were  not  fit  to  eat  and  the  peo- 
ple became  disgusted  with  this  specialty  in  so  much  that  even  the 
goods  of  highest  quality  moved  slowly  for  a  time. 

The  same  practice  injures  the  catsup  market  frequently.  To- 
mato canners  will  dump  their  tomato  peelings  into  open-head  bar- 
rels or  casks  and  perhaps  let  them  sour  and  almost  decompose  be- 
fore they  are  made  up  into  pulp  and  finally  into  catsup.  It  might 
be  remarked  that  catsup  made  from  such  material  will  keep  almost 
indefinitely  without  any  preservative.  The  lactic  acid  formed  dur- 
ing the  decomposition  of  the  peelings,  takes  the  place  of  vinegar  and 
preserves  the  catsup.  Some  of  the  strictly  pure  catsups  mentioned 
in  the  Agricultural  reports  are  manufactured  from  such  refuse, 
and  arguments  against  the  employment  of  chemical  preservatives  in 
fine  catsup  have  been  built  upon  the  facts  mentioned.  Fine  catsup 
requires  a  preservative  unless  it  is  sterilized.  The  effect  of  such 
poor  goods  thrown  on  to  the  market  injures  the  sale  of  even  the 
finest  grades,  because  people  become  dissatisfied  and  turn  to  other 
goods,  or  they  make  catsup  at  home  and  quit  buying  altogether. 

There  was  a  time  when  the  manufacture  of  jellies,  preserves, 
butters  and  jams  was  a  profitable  business ;  this  was  in  the  begin- 
ning, when  all  were  made  from  the  pure  fruits,  and  there  were  no 
imitations  or  adulterations  widely  known.  There  was  a  good  de- 
mand, and  the  profits  were  good,  but  when  the  imitations  and  adul- 
terations became  so  gross  that  the  goods  had  no  flavor  nor  resem- 
blance to  the  fruit  from  which  it  was  claimed  to  be  manufactured, 
the  people  quit  buying  the  stuff  and  the  prices  dropped  so  low  that 
there  was  no  inducement  to  pack  these  goods. 

Today,  however,  there  are  a  number  of  such  lines  manufac- 
tured from  strictly  first-class  material,  and  are  pure,  and  there  is 
quite  a  good  demand  for  them,  but  the  market  has  been  greatly  in- 
jured by  the  inferior  lines  and  it  will  require  time  to  restore  confi- 
dence. 


322  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

It  is  well  when  any  line  of  specialties  is  to  be  made  a  part  of 
the  business,  to  manufacture  such  goods  as  will  be  harmonious  with 
the  regular  line.  For  instance,  if  the  canning  of  tomatoes  is  to  be 
the  principal  product,  the  line  analogous  would  include  tomato 
catsup,  Chili-sauce,  and  perhaps  tomato  soup  and  goods  requiring 
tomato  sauce  or  other  delicacies  which  combine  nicely  with  toma- 
toes. It  is  surprising  how  naturally  the  side  lines  have  sprung  out 
and  helped  make  some  of  the  gigantic  institutions  identified  with 
the  food  industry. 

The  lines  which  have  sprung  out  of  the  dressing  of  meats  for 
the  market  are  the  canning  of  meats,  soups ;  also  extracts,  oils,  medi- 
cines and  chemicals,  and  other  lines  seemingly  to  have  no  connect- 
ion, and  yet  very  important  in  the  saving  of  material  formerly 
wasted. 

SEIvECTlON  OF  RAW  MATERIAIv. 

The  selection  of  raw  material  is  perhaps  the  most  important  of 
all  steps  in  the  art  of  canning  and  manufacturing  food  products. 
How  is  it  possible  for  a  firm  to  produce  goods  of  fine  quality  unless 
the  raw  material  is  of  the  very  best?  To  begin,  there  should  be  a 
thorough  understanding  with  the  growers  just  what  variety  is  to 
be  planted.  Vegetables  such  as  corn,  peas  and  tomatoes  should 
be  grown  according  to  contract,  and  it  is  a  good  plan  for  the  packer 
to  select  the  variety  or  furnish  the  seed  to  the  farmer.  If  toma- 
toes are  to  be  grown,  the  packer  should  decide  whether  he  intends  to 
manufacture  catsup  and  similar  products  at  the  same  time  and  fur- 
nish seed  for  the  varieties  which  produce  the  best  natural  color  and 
those  which  are  piquant  in  flavor.  If  the  packer  decides  to  pack 
corn,  he  should  select  the  seed  of  such  varieties  as  are  white  and 
sweet,  and  if  peas  are  to  be  canned,  the  varieties  should  be  only  those 
which  are  tender,  sweet  and  those  which  retain  their  natural  color 
wxll.  These  same  principles  should  be  applied  to  all  products  so 
far  as  possible.  The  next  step  is  the  contract  with  the  growers, 
which  should  be  as  strict  as  possible,  especially  covering  the  time 
of  harvesting  and  delivery.  All  farm  products  should  be  delivered 
on  the  same  day  when  they  are  taken  from  the  field.  As  we  have 
stated  in  previous  pages,  the  motto  should  be :  "From  the  field  to 
the  can  in  the  shortest  possible  time."  Raw  material  which  has 
stood  over  one  day  loses  much  of  its  flavor,  and  besides  offers  great 
objections  from  a  bacteriological  standpoint.  If  the  product  is 
wilted  or  softened  or  partially  decomposed  the  flavor  is  greatly  in- 
jured and  the  liability  to  spoilage  is  increased.  We  have  shown 
how  necessary  it  is  to  increase  the  time  for  sterilization  in  this  case, 
and  this  means  additional  loss  of  flavor,  so  that  the  result  of  it  all 
will  be  onlv  inferior  g-oods.     Durinsf  some  seasons  various  blights. 


THE  CANNING  INDUSTRY.  323 

rusts,  smuts  and  rots  attack  the  raw  material  and  cannot  be  avoided 
absolutely,  through  our  present  inability  to  cope  with  the  fungi  and 
molds  which  are  responsible ;  but  we  are  able  to  cut  away  such  por- 
tions and  use  only  the  good  parts.  Tomatoes  and  cabbage  are  li- 
able to  black  rot,  apples  are  sometimes  attacked  by  fungi,  also  other 
parasites,  and  if  these  parts  are  removed  the  good  parts  are  equal  in 
flavor  to  sound  fruit  so  far  as  I  have  been  able  to  determine,  because 
the  disease  is  only  local  and  does  not  affect  the  whole  fruit  unless, 
of  course,  it  has  advanced  too  far.  Whenever  possible,  however, 
only  perfectly  sound  material  should  be  used,  but  it  sometimes  hap- 
pens that  these  diseases  cannot  be  avoided  and  the  best  has  to  be 
made  of  the  matter. 

In  selecting  all  ingredients  which  enter  into  the  various  formu- 
las for  making  special  food  products,  the  very  best  are  to  be  used 
always.  It  may  be  necessary  to  make  analy^ses  of  some  to  determine 
their  purity  and  the  presence  of  colors  and  antiseptics,  and  a  careful 
study  of  the  official  analyses  given  in  Chap.  IX  will  be  found  ser- 
viceable. Wherever  possible  the  packer  should  familiarize  himself 
with  every  detail  of  his  business.  He  should  know  the  chemical 
composition  of  the  fruits  and  vegetables  he  cans,  also  the  food  value 
of  each,  and  should  study  the  effect  of  various  degrees  of  heat  on 
the  nutritious  properties.  Of  course  this  is  impossible  if  the  busi- 
ness is  large,  and  in  that  case  he  must  employ  men  who  are  able  to 
investigate  all  practical  and  scientific  problems  relating  both  to  raw 
materials  and  the  finished  goods. 


324  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

CHAPTER  XII. 

Peas 

History,  Growing,  the  Leguminous  and  Nitrifying  Bacteria,  the  Pea 
Parasite,  Chemical  Composition  and  Food  Value  of  Peas, 
Methods  of  Canning,  Machinery,  Bacteria  Associated  with  Spoil- 
age, as  Found  in  Various  Actual  Losses. 


HISTORY. 

The  garden  pea  belongs  to  botanical  order  of  Leguminosae,  in 
the  sub-order  Papilionaceae,  and  family  Sativum.  The  origin  of* 
peas  antedates  all  written  history,  since  early  records  show  that 
they  were  common  at  that  time  in  the  East.  Holland  seems  to  have 
been  the  first  European  country  to  cultivate  this  variety  of  pulse 
during  the  middle  ages,  and  from  that  country  they  were  introduced 
into  England,  and  then  the  seed  peas  were  probably  brought  over 
to  America  by  the  pilgrim  fathers.  There  are  two  kinds  of  peas, 
which  are  separated  botanically  into  distinct  families,  viz.,  the  field 
pea,  cultivated  as  feed  for  cattle,  and  the  much  esteemed  garden 
pea, ;  but  it  is  probable  that,  originally,  these  were  the  one  species, 
the  latter  having  undergone  marked  changes  under  special  care  of 
horticulturists,  until  it  now  yields  a  highly-prized  article  of  food. 

The  flowers  of  the  field  pea  are  red  and  only  one  to  each  flower- 
stock,  while  those  of  the  garden  pea  are  more  commonly  white,  sel- 
dom red,  and  there  are  two  or  more  to  each  flower-stock.  The  pea 
vine  is  a  climbing  annual,  having  pennate  leaves,  ovate  leaflets  and 
branching  tendrils. 

There  are  many  varieties  of  garden  peas  cultivated  especially 
for  canning  purposes,  and  these  are  selected  with  due  regard  for 
small  sizes,  sweetness  and  flavor,  since  the  small  sizes  are  in  great 
demand  and  bring  the  best  prices.  There  are,  however,  large  sizes 
of  the  wrinkled  variety,  which  are  very  sweet,  and  have  a  good 
market  at  all  times.  One  variety  often  grown  for  the  market,  be- 
cause of  its  excellent  yield,  has  black  eyes  and  very  little  flavor. 
When  canned  these  peas  have  a  mealy,  slightly  bitter  taste,  and  can- 
not compare  in  any  way  to  such  varieties  as  the  Little  Gem,  Alaska, 
Admiral  Advancer,  Horsford's  Market  Garden  and  others. 

The  canning  of  peas  originated  in  France  some  time  between 
1810  and  1820,  under  Appert  and  others  whose  names  are  not 
known  to  us.     Such  excellent  peas  have  been  cultivated  and  canned 


PEAS.  325 

in  France  that  their  reputation  is  almost  world  wide;  but  in  late 
years  there  has  been  too  much  artificial  coloring  with  copper  salts, 
and  there  is  considerable  objection  to  them  on  that  account.  The 
French,  however,  give  more  attention  to  the  cultivation  of  peas  than~ 
Americans,  and  have  as  a  result  a  much,  larger  per  cent  of  small 
sizes,  which  are  sweeter  and  more  palatable  than  the  larger  and 
more  matured  sizes. 

In  America,  pea  packing  began  about  i860  in  Baltimore,  and 
the  demand  became  so  great  that  the  industry  was  almost  unable  to 
meet  it,  although  every  canning  house  in  the  country  packed  them 
wherever  the  location  was  favorable  for  growing  them.  The  labor 
connected  with  picking  peas  in  the  fields,  and  hulling  them  at  the 
factories,  was  enormous,  and  this  expense  naturally  made  the  re- 
tail price  a  little  too  high  for  the  masses;  but  in  1890-1892  Messrs. 
Chisholm  &  Scott  overcame  the  difficulties  of  hulling  by  machinery, 
and  by  wonderful  genius,  machines  were  perfected,  which  no  longer 
necessitated  hand  work  either  in  the  field  or  the  factory,  so  far  as 
picking  and  hulling  were  concerned.  From  this  time  until  the  de- 
structive pea  louse  appeared  and  devastated  the  crops  of  peas  in 
many  places,  the  canning  of  this  popular  vegetable  increased  won- 
derftdly,  even  to  the  extent  of  over-production. 

All  varieties  of  peas  were  grown  and  in  localities  which  were 
unfavorable  the  peas  did  not  have  a  good  flavor,  so  that  the  quality 
of  a  certain  per  cent  of  those  packed  in  1891  and  1892  was  not 
strictly  first-class.  As  we  stated  in  the  last  chapter,  there  are  only 
certain  sections  of  the  country  well  suited  for  cultivating  peas.  The 
flavor  of  these  is  due  to  several  causes ;  the  climate  is  such  that  the 
growth  is  rapid,  consequently  the  peas  are  very  tender  and  sweet, 
the  soil  is  particularly  adapted  to  the  development  of  the  nodules 
or  legumes,  which  are  excrescences  from  the  roots,  and  have  the 
power  of  fixing  the  free  nitrogen,  which  is  then  used  by  the  plants 
themselves.  These  nodules  are  bacteria,  and  are  termed  nitrogen- 
iixing  bacteria  and  bacteroids. 

The  nitrifying  bacteria  also  assists  in  the  formation  of  nitro- 
gen salts,  which  are  used  by  the  growing  plants,  so  that  soil  which 
contains  large  numbers  of  these  microscopical  organisms  furnishes 
the  best  possible  condition  for  the  growth  of  peas. 

Peas  grow  well  in  chalky  and  other  calcareous  soils,  but  a  fine 
growth  depends  almost  entirely  upon  the  presence  of  bacteria  we 
mentioned,  and  it  is  possible  to  prepare  the  conditions  artificially, 
which  will  secure  a  fair  yield  even  in  most  unfavorable  locations, 
by  making  pure  cultures  of  these  bacteria  and  mixing  them  with 
the  seed  when  planted,  so  it  is  probably  well  that  we  make  a  closer 
examination  and  study  of  these  minute  organisms  which  are  so  use- 
ful. 


326  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

ASSIMII.ATION  OF  NITROGEN. 

The  sources  of  nitrogen  for  the  use  of  plants  are :  The  atmos- 
phere (which  contains  about  79  per  cent  by  volume)  ;  the  nitrates 
and  nitrous  acid  formed  in  the  soil  and  air:  ammonia  (produced  by 
the  putrefaction  of  dead  matter)  ;  manure  and  fertilizers,  which 
contain  nitrogenous  compounds ;  and  from  the  tissues  of  plants  and 
animals.  Plants  cannot  of  themselves  use  nitrogen  in  free  form, 
so  it  must  first  be  fixed  in  combinations  suitable  for  its  assimilation. 
The  value  of  fertilizers  lies  in  the  amount  of  nitrate  of  soda  which 
they  contain,  and  this  salt  is  found  naturally  in  Chile  and  Peru, 
South  America,  w^here  it  has  accumulated  for  hundreds  of  years  by 
the  nitrogen-fixing  bacteria,  which  use  the  free  nitrogen  of  the  air 
and  combine  it  with  soda,  so  plentiful  in  those  regions.  These  ni- 
trate beds  are  being  exhausted  rapidly,  however,  nearly  one  and  a 
half  million  tons  being  exported  annually,  the  value  being  about  $65 
a  ton.  Nitrate  of  soda  is  used  in  such  lar^  quantities  in  various 
industries  that  the  supply  for  fertilizing  is  growing  less,  and  it  is 
estimated  that  within  fifty  years  the  natural  beds  will  be  exhausted ; 
so  some  other  means  of  obtaining  the  salt  for  plant  life  is  a  problem 
which  is  open  for  solution  by  every  one.  Since  the  discovery  that 
certain  bacteria  have  the  power  of  utilizing  the  free  nitrogen  of  the 
air,  and  are  able  to  fix  it  with  soda,  it  has  been  discovered  that  cer- 
tain plants  have  a  tendency  to  form  legumes  or  tubercles  upon 
their  roots,  and  that  these  are  nothing  more  or  less  than  nitrogen- 
fixing  bacteria,  which  supply  the  plant  itself  with  the  nitrogen  ele- 
ments, so  that  the  bacteria  themselves  are  used  by  the  plant  and 
are  its  hosts,  contrary  to  the  general  system  seen  in  nature,  where 
the  breaking  down  of  animal  and  vegetable  protoplasm  is  a  source  of 
life  and  energy  for  the  development  and  growth  of  fermentative, 
putrefactive  and  parasitic  micro-organisms. 

The  green  pea  is  one  of  the  species  of  plants  which  invites  the 
nitrogen-fixing  bacteria,  and  at  first  furnishes  them  the  elements 
necessary  for  their  growth,  afterward  claiming  them  for  its  own  ex- 
istence and  building  up  a  healthy  stem  with  flowering  branches, 
gives  evidence  of  its  well  nourished  condition  in  the  well  filled  pods 
of  tender,  sweet  peas,  so  earnestly  sought  by  all  lovers  of  this  fine 
flavored  garden  pulse. 

When  peas  are  planted  in  a  soil  containing  all  the  elements  for 
growth  excepting  nitrogen,  they  will  thrive  well  if  there  are  any 
nitrogen-fixing  bacteria  present,  because  these  little  workers  will 
build  up  the  nitrates  for  the  plants,  but  if  none  of  these  are  present 
the  growth  is  poor,  because  they  must  feed  upon  the  carbohydrates, 
albumen,  fat,  etc.,  accumulated  in  the  seed-leaves,  so  when  this  sup- 
ply is  exhausted  the  plants  cease  growing,  and  the  leaves  lose  their 
chlorophyl,  turning  )^ellow,  and  there  is  perhaps  no  disposition  to 


PEAS.  327 

bear  the  pods.  The  plants  in  this  case  are  suffering  from  what  is 
termed  nitrogen  hunger.  When  at  this  stage,  if  the  soil  near  the 
root  be  moistened  with  water  containing  the  nitrogen-fixing  bac- 
teria, wonderful  changes  will  be  noticed  in  a  short  time.  The 
stock  and  branches  will  grow  stronger,  the  leaves  will  turn  green, 
and  the  pods  will  fill  with  peas  rapidly.  In  order  to  properly  grow 
peas  in  some  localities  where  very  poor  or  only  occasional  crops 
are  obtained,  a  means  is  now  offered  to  the  packer  of  helping  the 
growers  to  obtain  good  crops  at  all  times,  and  this  discovery  is  of 
course  valuable  to  canners,  because  they  must,  to  a  certain  extent, 
be  guides  for  the  farmers,  who  do  not,  as  a  rule,  keep  posted  on  sci- 
entific researches  in  agriculture. 


.^4  ^ 


V 


Plate  99.     Nitrogen  Fixing  Bacteria 

Photomicrograph    X    1,000.     Bacillus    Radicicola,    rod    forms   cultivated   on   special   agar 
mitrient   medium.      Stained   with  Fuchsin. 

In  1 888  Beyerinck  made  the  discovery  that  the  nodules  of 
tubercles  on  the  roots  of  plants  belonging  to  the  order  of  Legumin- 
osse  were  composed  of  bacteria  which  had  changed  from  simple 
motile  rods  into  a  complete  involutionary  form,  having  no  resem- 
blance to  the  original  micro-organisms  whose  protoplasm  had  been 
used  to  build  up  bacteroidal  tissue.  He  obtained  pure  cultures  from 
the  nodules,  and  used  the  leaves  of  the  plant  with  the  addition  of  7 
per  cent  gelatin,  J4  P^^  cent  asparagin  and  J^  per  cent  of  cane  sugar, 
as  a  solid  culture  medium  for  isolating  them. 

To  cultivate  them  in  pure  cultures,  we  take  a  nodule  from  the 
roots  of  the  pea  and  wash  it  with  water,  then  steep  it  in  absolute  al- 
cohol for  about  two  minutes,  and  then  drive  off  the  alcohol  with 
ether.  The  nodule  is  then  cut  open  and  a  portion  of  the  bacteroidal 
tissue  is  introduced  into  a  small  qtiantity  of  water,  which  has  been 
sterilized  in  a  cotton-plugged  test  tube  at  250  degrees  F.  for  twenty 


328  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

minutes.  After  the  infusion  has  stood  a  while,  the  Petri  dishes 
containing-  the  nutrient  medium  previously  described  are  moistened 
on  the  surface  with  drops  of  the  infusion ;  the  gelatin  will  absorb  the 
water  and  leave  the  germs  free  on  the  surface.  These  will  develop 
and  form  small  mucinous  colonies,  which  do  not  liquefy  the  gelatin, 
and  streak  cultures  may  be  made  from  these.  Two  varieties  of 
micro-organisms  are  thus  separated,  one  which  has  been  named 
Bacillus  radicicola  rods,  is  about  i  /*  broad  and  3  to  4  /^  long.  They 
are  strongly  aerobic  and  may  be  seen  to  seek  the  air  bubbles  under 
the  coverglass  or  to  wander  towards  the  edge  of  the  glass.  The 
other  variety,  called  Bacillus  radicicola  rovers,  is  exceedingly  small, 
being  only  about  0.9  /x  long  and  0.18  /x  broad;  they  are  motile,  pos- 
sessing a  single  terminal  flagellum,  which  is  about  twenty  times  as 
long  as  the  cell,  and  gives  it  a  very  rapid  movement,  which  enables 
it  to  break  away  from  the  parent  colony  and  travel  rapidly  across 
the  surface  of  the  gelatin.  The  germs  are  so  small  that  they  readily 
pass  through  the  Charaberland  filter  and  escape  ordinary  notice  in 
stained  coverglass  preparations. 

The  author  is  indebted  to  George  T.  Moore,  physiologist  in 
charge  of  Laboratory  of  Plant  Culture,  Bureau  of  Plant  Industry, 
for  his  first  cultures  of  these  organisms,  but  we  have  obtained  even 
better  cultures  for  peas  from  the  young  nodules  previously  de- 
scribed, and  pure  cultures  are  now  grown  in  the  National  Canners' 
Laboratory  and  these  are  free  to  all  subscribers  for  distribution 
among  growers  whose  ground  seems  unfavorable  at  times  for  pro- 
ducing good  crops  of  peas.  It  is  possible  to  take  a  dry  culture  con- 
taining millions  of  these  germs,  and  inoculate  a  quantity  of  rain 
water  specially  prepared  with  nutrient  material,  and  after  a  few 
days  soak  the  seed  peas  in  the  water,  and  plant  them,  or  the  manure 
that  goes  into  the  field  may  be  moistened  with  such  water,  and 
the  bacteria  may  thus  be  distributed  over  a  field  in  such  a  manner 
that  the  crop  of  peas  will  be  twice  as  great  as  is  ordinarily  grown 
on  the  same  ground. 

The  bacteria  which  prove  so  valuable  in  fixing  the  atmospheric 
nitrogen  for  the  benefit  of  peas,  have  a  peculiar  life  history.  They 
are  widely  distributed,  in  the  air,  water  and  soil,  but  are  frequently 
absent  in  some  localities,  or  if  not  entirely  absent,  are  so  few  in 
numbers  as  to  be  of  little  value  to  the  peas  sown  in  such  places.  If 
the^eed  peas  be  moistened  in  water,  which  has  received  a  pure  cul- 
ture, they  will  be  carried  into  the  ground  and  will  be  able  to  grow 
and  multiply  rapidly  as  soon  as  the  tiny  hair-like  roots  begin  to  force 
themselves  downward  into  the  soil. 

The  roots  absorb  the  moisture  from  the  soil,  and  through  the 
epidermal  cells,  the  bacteria  gain  entrance  and  rapid  multiplication 
takes  place  by  the  fission  process,  so  that  in  a  short  time  the  sap 


PEAS. 


329 


is  teeming  with  countless  myriads  of  these  tiny  organisms,  which 
fill  up  all  the  channels,  multiplying  until  this  cycle  of  their  life 
history  is  accomplished. 

The  bacteria  are  seen  to  be  gathered  into  colonies  in  various 
places  where  hard  membranes  surround  them,  and  sacs  are  formed 
which  grow  outward  and  beyond  the  bark  cells  of  the  roots,  so  that 
tubercles  or  nodules  are  formed  and  these  become  hard  and  present 
the  appearance  of  tissue.  The  tissue  is  formed  by  the  bacteria 
themselves,  which  no  longer  have  any  of  their  original  characteris- 
tics or  forms,  but  are  matted  together  into  bacteroidal  tissue,  which 


Plate  100.     Noduic  Bactcna  Radicola 

Section  of  a  Nodule,  a  Shows  Cell  Containing  Bacteroids,  b  Shows  the  Infected 
Thread,   Photomicrograph  X  1,000. 

is  called  by  A.  B.  Frank,  mycoplasma.  The  name  which  has  been 
given  to  these  cells  is  ''bacteroids,"  which  indicates  their  origin 
from  bacteria.  The  bacteroids  are  rich  in  albumen,  and  never 
again  grow  into  the  rod  forms,  seeming  to  have  entirely  lost  repro- 
ductive power.  The  accompanying  plates  will  give  some  idea  of 
the  changes  which  the  bacteria  undergo  from  the  rods  to  the  forma- 
tion of  the  nodule  tissue. 

It  will  be  noticed  that  slight  swellings  appear  at  the  ends,  which 
begin  to  divide  into  branches  or  forks,  later  taking  on  distinct  Y 
forms,  which  unite  and  form  a  mesh  work,  or  reticulated  bands. 
Within  this  meshwork  are  frequently  found  rod-shaped  bacteria 
which  seem  to  have  escaped  the  involution  which  has  affected  others 
of  their  kind,  and  these  bacteria  may  be  employed  to  start  pure  cul- 
tures on  specially  prepared  nutrient  media. 


330  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

According  to  A.  B.  Frank,  the  nodules  formed  on  the  roots  of 
peas,  differ  from  those  of  other  Leguminosae,  in  chemical  composi- 
tion, and  contain  besides  albumen,  carbohydrates,  which  he  names 
amylodextrins;  but  other  investigators  have  shown  that  the  socalled 
amylodextrins  were  fatty  substances. 


,^  pry 


»  ^ 


Plate  101.     Bacillus  Radicicola 


Showing    the    Young    Rods    Attained    from    a    Root    Nodule.      Photomicrograph 
Magnified  2,000  Diameters. 


■^V.^ 


Plate  102.     Bacillus  Radicicola 

Showing  the  Beginning  of  Involution,   Clubs  and  Branches  in  Y  shapes.    These 
Forms  are  not  Motile.     Photomicrograph  X  2,000. 

As  the  tubercles  grow  older  they  increase  in  size,  and  con- 
tain larger  amounts  of  nitrogenous  substances  which  are  utilized 
rapidly  by  the  peas,  resulting  in  abundant  stalks,  leaves,  flowers  and 
pods  containing  the  green  vegetable  coloring  matter  called  chloro- 
phyl,  so  much  esteemed  for  appearance  in  canned  peas.  The  chlor- 
ophyl,  therefore,  is  most  abundant  where  the  peas  are  well  supplied 


PEAS. 


331 


with  nitrogen  from  the  root  nodules.  The  accompanying  Figure 
No  20  will  show  the  young  nodules  clinging  to  the  roots  and  cross 
sections  magnified  to  give  some  idea  of  their  appearance. 


Plate  103.     Nodules  on  the  Roots  of  Peas 

Showing    Many    Nodules.     From    Photograph    in    Year    Book    of    Department   of 
Agriculture. 

J.  Stoklasa  has  made  a  number  of  quantitative  analyses  of  dried 
roots  from  peas,  clover  and  other  Leguminosse,  to  determine  the 
amount  of  nitrogen  present,  and  the  results  are  here  given. 


Nitrogen  Content  in  the 
Dry  Matter  From 

At  Flowering 
Time. 

At 
Fructification 

In  Fullv 
Riped  Pods. 

Root  Nodules 

5  2  per  cent. 
1.6  per  cent. 

2.6  per  cent. 
1.8  per  cent. 

1.7  per  cent. 

Root  free  from  Nodules               

1.4  per  cent. 

The  nitrogen  is  combined  in  three  forms  principally  in  Albu- 
men, and  also  in  Amides,  and* Aspar agin,  as  follows : 


Percentage   Content  of  the   Dry  Sub- 

In Nitrogen  as 

stance  of  the  Nodules. 

Albumen 

Amides 

Asparagin 

Flowering  time 

Ripened  pods 

3.99  per  cent.      O..S0  per  cent. 
1.54  per  cent.  ,   0.15  per  cent. 

0.34  per  cent, 
traces 

Other  investigators  have  obtained  as  high  as  6.94  per  cent  of 
nitrogen  from  the  dry  nodules  of  peas. 


332 


CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


The  bacteria  found  in  the  nodules  of  various  species  of  Legu- 
minosse,  look  very  similar  under  the  microscope,  there  being  no 
apparent  difference;  but  experiments  have  proven  that  there  are 
great  differences  in  results  obtained  with  various  pure  cultures. 


Plate  104 

Photograph  of  the  roots  of  pea  vine  showing  the  formation  of  the  bacteroidal  nodules.  These  peas 
were  soaked  in  water  inoculated  with  Bacillus  Radicicola  and  there  are  numbers  of  nodules  which  gather  the 
nitrogen  from  the  atmosphere  and  fix  it  for  the  plants.  The  vines  are  very  hardy,  standing  over  three  feet  high, 
having  stems  as  thick  as  a  lead  pencil. 


Clover  planted  in  sterilized  earth  and  watered  with  an  infusion 
of  the  bacteria  cultivated  from  the  tubercles  of  peas,  does  not^form 
nodules,  consequently  grows  poorly,  withers  and  dies,  and  the  re- 
verse is  also  true.  If  peas  planted  in  the  sterilized  soil  be  watered 
with  an  infusion  of  bacteria  from  the  tubercles  of  clover  roots. 


PEAS.  333 

they  soon  dry  while  if  the  bacteria  are  taken  from  the  tubercles  of 
peas,  the  growth  will  be  luxuriant  under  favorable  conditions.  This 
great  similarity  of  species  is  not  confined  to  the  nitrogen-fixing  bac- 
teria ;  in  our  investigation  of  spoilage  in  canned  vegetables,  we  have 
met  many  species  which  so  closely  resembled  each  other  as  to  de- 
ceive us,  except  in  the  products  elaborated  by  them  when  growing 
under  certain  influences. 

The  nitrogen  fixing  bacteria  are  soon  to  receive  considerable 
attention  in  our  Agricultural  Stations,  and  some  important  results 
may  be  expected  in  the  near  future.  The  very  fact  that  organisms 
which  are  capable  of  working  up  atmospheric  nitrogen  into  nitro- 
genous compounds  so  necessary  for  plant  life,  opens  up  a  means  of 
preparing  barren  wastes  for  the  cultivation  of  all  kinds  of  fruits 
and  vegetables. 

Whenever  crops  of  any  plants  belonging  to  the  order  of  Legu- 
minosae  are  sown,  and  nitrogen  fixing  bacteria  are  introduced  in 
pure  cultures,  there  is  a  wonderful  increase  of  nitrogenous  com- 
pounds accumulated  in  the  soil,  which  enriches  it  with  all  the  re- 
quirements of  plant  life  in  general.  This  is  the  reason  that  ground 
sown  in  clover  is  so  greatly  benefited  for  the  cultivation  of  farm 
and  garden  truck  in  following  seasons. 

There  are  two  other  species  of  bacteria  present  everywhere  in 
all  kinds  of  soil,  which  have  a  wonderful  field  of  usefulness  in  sup- 
plying food  for  plant  life,  and  their  work  is  oxydation  of  the  nitro- 
gen from  ammonia,  into  nitrous  acid  by  one  class,  and  then  further 
converting  this  into  nitric  acid  by  the  other,  thus  nitrites  are  formed 
from  ammonia,  and  nitrates  are  formed  from  the  nitrites,  so  they 
have  been  significantly  named — nitrifying  bacteria.  These  two 
classes  of  bacteria  are  always  present  side  by  side,  because  the  ele- 
ments necessary  for  the  multiplication  of  the  nitrate  bacteria  are 
formed,  of  course,  by  the  nitrite  micro-organisms.  The  value  of 
manure  and  decomposing  animal  and  vegetable  matter  as  fertilizers 
lies  in  the  amount  of  nitrogen  which  these  substances  contain,  but 
this  nitrogen  cannot  at  once  be  utilized  by  plant  life,  consequently 
the  oxydation  processes  we  have  described  above,  must  be  accom- 
panied by  the  nitrifying  bacteria. 

The  discovery  of  the  nitrifying  bacteria  was  made  (in  1888) 
by  S.  Winogradsky,  a  Russian  investigator,  who  made  pure  cul- 
tures from  soil  obtained  in  various  parts  of  the  world,  principally 
from  Europe,  Africa,  Japan,  Java,  Brazil  and  Quito  (Ecuador). 

The  soils  from  these  countries  contained  difTerent  species  which 
he  was  able  to  isolate  and  grow  in  pure  cultures,  not,  however,  on 
the  usual  nutritious  culture  media  employed  in  ordinary  bacterio- 
logical  work,   because   the    nitrifying    bacteria    are    prototrophic 


334  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

Strictly,  and  must  be  supplied  with  material  suitable  for  their  de- 
velopment. 

A  fluid  culture  medium  was  employed  as  follows : 

Water   looo  c.  c. 

Magnesium  Carbonate 0.5  grams 

Magnesium  Sulphate   0.3  grams 

Diabasic  Potassium  Phosphate 0,2  grams 

vSodium  Chlorid 0.5  grams 

A  solid  culture  medium  may  be  prepared  with  these  ingredi- 
ents using  colloid  silica,  instead  of  the  ordinary  gelatin  or  agar. 


^ 

'. 

^•i 

«k^- 

^, 

Plate  105.  ■  Nitrosomonas  Europea 
Showing  F"lagellum  at  end  of  each  Germ.     Photomicrograph.    Magnified  1500  diameters. 

NITROSOMONAS  BUROPBA,  is  nearly  round,  being 
about  0.9  to  I  IX  broad,  and  from  1.2  to  1.8  />i  long,  and  is  found  in 
European,  African  and  Japanese  soil.  It  is  a  nitrite  bacterium,  and 
motile,  possessing  a  single  rather  short  flagellum.  It  grows  in  short 
chains  of  three  or  four  members,  and  no  spore  formation  has  been 
observed.     The  colonies  on  silicic  acid  media,  are  brown. 

N'itrosomonas  Javanensis,  another  species,  is  almost  round;  is 
motile,  having  a  single  flagellum  about  30  ix  long,  which  is  the 
longest  organ  of  locomotion  I  have  ever  seen,  being  some  sixty  times 
longer  than  the  cell  itself.  It  grows  well  on  silicic  acid  medium, 
and  the  colonies  are  similar  to  the  bacterium  previously  described. 
It  forms  zooglea  in  liquid  cultures,  and  collects  on  carbonate  of 
magnesium  crystals  in  slimy  masses,  and  disintegrates  them.  After 
twenty-four  hours  the  germs  all  drop  to  the  bottom,  and  the  pro- 
duction of  nitrites  ceases. 

The  nitrate  bacteria  are  the  organisms  which  form  nitrates 
from  the  nitrites  which  result  from  the  action  of  the  nitrosomonas 
just  described.     They  are  exceedingly  small,  and  somewhat  pear- 


PEAS.  335 

shaped  in  form,  and  are  able  to  pass  through  the  pores  of  the  Cham- 
berland  filter. 

Winogradsky  discovered  the  nitrate  bacteria  in  the  soil  always 
where  the  nitrite  bacteria  were  found,  and  he  gave  them  the  name 
of  Nitrohacter.  They  are  not  motile,  and  in  liquid  cultures  form 
a  thin  mucinous  skin  which  clings  firmly  to  the  floor  and  walls  of  a 
culture  flask.  No  spore  formation  has  been  observed,  and  no  divis- 
ion of  species  has  been  attempted. 


Plate  106.     Green  Pea  Louse 

There  are  great  possibilities  in  the  cultivation  of  peas  in  un- 
favorable locations,  and  it  is  possible  that  much  larger  and  better 
crops  may  be  grown  in  localities  where  even  a  fair  yield  is  now 
obtained.  There  should  be  extensive  experimental  work  done,  with 
soil  inoculated  with  pure  cultures  of  nitrogen-fixing  bacteria  and 
the  nitrifying  bacteria.  It  is  possible  for  the  packers  to  obtain  pure 
culture  of  these  bacteria  from  the  laboratory  and  distribute  them 
among  their  growers.  If  these  experiments  are  properly  conducted, 
we  predict  that  a  very  large,  quick  growth  of  peas  may  be  obtained, 
and  that  they  will  be  more  uniform  and  more  tender  and  better  in 
color  than  those  generally  grown  for  canning  purposes. 

The  experiments  with  nitrogen-fixing  bacteria  have  been  car- 
ried on  by  the  Agricultural  Department  in  the  Bureau  of  Plant  In- 
dustry for  some  time  by  George  T.  Moore,  and  the  results  are  en- 
couraging. 

It  is  not  expected  that  the  packers  will  be  able  to  pursue  the 
study  and  cultivation  of  these  organisms,  but  if  they  become  inter- 
ested, as  they  should,  and  willing  to  bear  the  expense  of  experi- 
menting, it  is  almost  certain  to  bring  good  returns  for  the  outlay. 

There  are  various  methods  for  cultivating  peas  for  canning 
purposes  which  all  growers  follow,  but  it  is  not  within  the  scope  of 
a  work  of  this  kind  to  enter  into  any  elaborate  description  of  agri- 


336 


CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


cultural  subjects.  The  employment  of  scientific  methods  for  ob- 
taining good  results  must  ever  be  interesting  to  the  packer  as  well 
as  the  grower.  It  may  be  possible  to  employ  bacteriological 
methods  for  the  extermination  of  such  parasites  as  the  pea  louse  and 
other  insects  which  are  so  destructive  at  times. 

PARASITES   OF   THE    PEA    PLANT. 

*There  are  some  parasites  which  thrive  on  the  leaves,  pods, 
and  stems  of  peas  belonging  to  the  fungi.  Among  these  are  the 
smuts,  which  produce  black  patches  composed  of  micro-organisms 
of  a  higher  order  than  bacteria,  but  which  belong  entirely  to  the 
vegetable  kingdom  and  multiply  at  the  expense  of  the  plant  tissue 
and  sap.  The  rusts  are  also  of  the  same  order,  and  frequently  at- 
tack the  pods  so  that  large  round  spots  appear  all  over  them,  and 
sometimes  the  tissue  is  perforated  so  that  bacteria  gain  access  to  the 
peas  themselves. 


1 

Plate  107.     Green  Pea  Lice 

A.    fourtTi   stage   wingless   femade;    B.    wingless    viviparous    female    and   young; 
C,   pupa;   D.   winged  viviparous  female. 

The  damage  done  by  these  fungi  is  not  very  serious,  however, 
in  comparison  to  insect  parasites.  The  green  pea  louse  (Nectaro- 
phora  pisi  Kalt)  or  green  fly  (so  styled  by  Prof.  H.  G.  Johnson  of 
the  Maryland  Agricultural  College),  which  made  its  first  appear- 
ance in  1899,  has  done  more  damage  than  all  other  pests  known 
to  canners.     The  destruction  of  peas  in  1899,  1900  and  1901  prob- 


*The  photographs  shown  on  this  subject  were  taken  by  Prof.  San- 
derson and  Prof.  Johnson,  to  whom  we  are  indebted. 


PEAS.  337 

ably  amounted  to  se^'eral  millions  of  dollars.  The  destruction  of 
peas  was  grea^test  during  the  season  of  1899,  particularly  of  all  late 
varieties.  The  whole  Eastern  section  of  this  country  and  Canada, 
wherever  peas  were  grown,  .suffered  almost  total  losses ;  fields  em- 
bracing a  hundred  acres  were  devastated  as  if  by  fire ;  so  rapid  was 
the  multiplication  of  the  insect  that  it  proved  utterly  impossible  to 
save  the  crops  by  any  spraying  or  brushing  methods  known.  The 
common  method  of  planting  by  sowing  broadcast  had  much  to  do 
with  the  difficulty  of  combating  the  progress  of  the  scourge,  be- 
cause there  was  no  room  between  the  vines  for  brushing  and  spray- 
ing with  kerosene,  and  soap-suds  proved  ineffective  for  the  same 
reason,  and,  also,  because  the  lice  bred  upon  the  imderside  of  the 
leaves  or  between  the  folds  in  such  a  position  that  a  spray  could  not 
reach  them. 

The  life  history  of  the  green  pea  fly  is  not  as  yet  complete,  but, 
according  to  Prof.  Johnson,  and  Prof.  J.  G.  Sanderson  (who  read 
papers  at  Detroit,  Rochester  and  Milwaukee),  it  seems  certain  that 
the  insect  is  common  as  a  parasite  of  all  plants  belonging  to  the  legu- 
menos^e,  such  as  peas,  beans,  clover,  vetch,  et  al.,  and  may  have 
been  growing  unobserved  for  many  years  without  having  attracted 
any  particular  attention.  I  had  a  most  remarkable  illustration  of  its 
reproductive  powers  on  beans,  (navy  pea  beans),  which  were  piled 
in  sacks.  In  some  manner,  the  bottom  layers  became  wet  and  were 
not  discovered  for  about  a  month.  The  bags  had  rotted  and  the 
beans  had  been  attacked  by  this  identical  insect,  which  destroyed 
fully  fifty  per  cent.  We  swept  up  fully  a  barrel  full  of  the  dead 
flies  which  are  about  1-32  of  an  inch  long.  I  also  found  a  few  live 
ones,  but  nearly  all  seemed  to  have  perished  most  unaccountably. 
The  cause  of  their  destruction  I  found  to  be  due  to  a  fungus  disease 
and  Avill  speak  of  it  a  little  further  on. 

The  lice  are  hatched  from  eggs  after  the  cold  weather  is  over, 
and  from  that  time  on  until  winter,  reproduction  is  carried  on  by 
the  mother  flies  giving  birth  to  living  young.  The  average  life  of 
a  female  fly  is  a  little  more  than  one  month  and  during  that  time  she 
will  bring  into  existence  about  150  young  ones.  According  to  the 
observation  of  the  two  gentlemen  previously  mentioned,  there  are 
no  males  among  them,  although  two  or  three  instances  pointed  to 
their  existence.  There  are,  of  course,  stages  in  the  life  history  of 
the  green  fly,  when  the  males  are  in  evidence,  most  likely  some  time 
in  the  fall  of  the  year,  at  which  time  it  is  possible  that  the  females 
are  made  capable  of  producing  young  which  in  their  turn  receive  the 
vital  principal  from  the  mother.  The  many  peculiarities  of  this 
kind  familiar  to  the  entomologist  do  not  cause  much  surprise,  be- 
cause nature  has  endowed  many  species  of  insects  with  wonderful 
powers  of  reproduction,  and  other  peculiar  morphological  and  bio- 
logical characteristics. 


338  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

It  has  been  demonstrated  that  cold  weather  does  not  kill  the 
insect  which  may  be  frozen  stiff,  but  after  thawing  will  be  as  active 
as  ever,  and  is  still  able  to  give  birth  to  its  young.  In  certain  sec- 
tions of  the  country,  after  having  been  visited  with  freezing  weather 
in  December,  the  insects  were  found  alive  after  a  thaw,  and  some 
were  still  observed  as  late  as  January  on  clover. 

There  are  certain  seasons  when  insect  pests  of  various  kinds 
arrive  in  different  parts  of  the  world  in  innumerable  hosts,  and  de- 
vastate vegetation,  but  after  a  time  disappear  in  a  manner  almost  as 
unaccountable  as  their  appearance.  Nature  has  endowed  insects 
with  wonderful  reproductive  powers  because  of  their  many  enemies, 
such  as  birds,  animals,  and  other  insects  which  feed  upon  them.  It 
is  strangely  true  that  the  enemies  of  insect  life  are  nearly  always 
present  in  sufficient  numbers  to  prevent  scourges,  such  as  those 
which  h^ve  destroyed  peas  during  the  past  few  years ;  but  it  some- 
times happens  that  their  greatest  enemies  are  not  present  in  sufficient 
numbers  to  prevent  an  overwhelming  multiplication.  We  have 
mentioned  birds,  animals  and  other  insects  as  enemies  (of  the  pea 
lice),  but  the  work  of  extermination  by  these  is  as  nothing  compared 
to  that  caused  by  parasites  which  spread  disease  among  them. 
These  parasites  may  belong  to  the  order  of  fungi  in  some  cases, 
often  they  are  disease-producing  bacteria  which  attack  the  vitals  and 
reproductive  organs  of  the  insects,  so  that  all  the  young  soon  die 
after  they  are  born. 

As  an  illustration  of  this  truth,  we  will  mention  some  fungi  and 
bacteria,  which  are  parasitic  to  insects  such  as  silk-worms,  bees  and 
caterpillars. 

In  1863  to  1865  the  whole  silk  industry  of  France  and  Italy 
was  almost  paralyzed  by  a  disease  started  among  the  silk  worms, 
w^hich  deprived  them  of  their  power  to  spin  cocoons.  Pasteur  un- 
dertook the  task  of  discovering  the  cause,  and  found  that  a  disease, 
which  was  called  Pehrine,  of  bacterial  origin,  had  spread  so  rapidly 
and  affected  the  moth  worms  and  eggs  to  such  an  extent  that  there 
seemed  little  hope>of  saving  the  indvistry.  He  retired  from  the 
world  and  began  his  investigations,  wdiich  resulted  in  his  being  able 
to  detect  the  disease  in  the  moth.  He  would  permit  a  moth  to  de- 
posit her  eggs  on  a  small  linen  cloth,  then  he  would  crush  her  body 
in  a  mortar  with  a  small  quantity  of  water.  A  microscopical  ex- 
amination would  reveal  the  presence  of  corpuscular  matter  perhaps, 
and  the  remains  together  with  the  eggs  were  destroyed.  Whenever 
a  moth  ^^•as  found  to  be  perfectly  free  from  the  bacteria  her  eggs 
were  carefully  set  aside  for  use  and  in  this  manner  the  healthy 
worms  were  again  cultivated. 

From  the  diseased  eggs,  pupae  and  moths  have  been  cultivated, 
shining  oval  micrococci,  2  to  3  ai  long,  2  ix  wide,  and  rods  2.5  /a 


PEAS. 


339 


broad  and  5  /*  long,  which  are  the  cause  of  Pchrine  and  Gattine  and 
are  named  by  Lebert  (Panhistophyton  ovatum).  Streptococcus 
bombycis,  are  oval  cocci  occuring  in  chains  and  pairs,  which  cause  a 
disease  among  silkworms  called  (flacherie),  which  causes  them  to 
cease  feeding  and  become  putrid. 

Honey  bees  are  sometimes  attacked  by  a  disease  called  foul- 
brood,  which  is  quite  common  in  this  country.  The  disease  attacks 
the  larvcC,  is  contagious  and  causes  them  to  die,  putrefy,  and  turn 
dark  brown  in  color.  The  cells  containing  diseased  larvae  may  be 
detected  easily  by  the  dark  cappings.  Foul-brood  is  a  disease  caused 
by  Bacillus  Alvei — rods  varying  in  size  which  form  large  oval 
spores.     The  bacteria  are  actively  motile. 

An  infectious  disease  called  Caterpillars'  Disease,  has  been  ob- 
served among  their  larvae.  The  bacteria  causing  their  destruction 
are  Cocci  united  in  pairs  and  chains. 


Plate  108.     American  Syrphus  Fly 


A.  larva  or  maggot  eating  a  pea  louse;  B.  puparium,  or  pupa  case,  from  which 
adult  fly  has  emerged,  end  broken  open;   C.   adult  fly. 


Returning  to  the  green  fly  so  destructive  to  pea  vines,  we  find 
a  number  of  natural  enemies  which  feed  upon  them.  There  is  a  fly 
considerably  smaller  than  the  green  lice,  which  lay  eggs  upon  their 
bodies  and  when  these  hatch  they  feed  upon  and  destroy  the  lice 
themselves  and  use  their  bodies  as  shelter  until  they  are  transformed 
into  flies,  when  they  emerge  through  openings  made  themselves 
and  seek  out  other  green  lice  as  hosts  for  their  eggs.  Large  num- 
bers of  pea  lice  are  thus  exterminated. 


340 


CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


Even  more  destructive  to  the  pea  lice  are  the  maggots  of  the 
syrphus  flies,  of  which  there  are  three  or  four  varieties.  These  flies 
are  beautifully  banded  and  lay  their  eggs  among  the  colonies  of 
lice,  for  instinct  leads  them  to  provide  a  suitable  food  location  for 
the  newly  hatched  maggots,  accordingly  when  they  hatch  they  begin 
to  feed  upon  the  thriving  colony  of  lice  surrounding  them,  and  the 
numbers  required  for  nourishment  very  soon  depletes  the  colony. 
These  maggots  or  worms,  so  often  seen  among  the  pea  vines,  are 
green  or  brown  in  color,  about  a  half  inch  in  length.  They  have  no 
legs  nor  head  apparently,  but  are  provided  with  two  powerful  hooks 
with  which  they  seize  the  lice,  and  hold  them  while  they  suck  the 
fluid  from  their  bodies. 


Fig.  32 

The  lady-bird  beetles,  of  which  there  are  several  varieties,  find 
in  the  pea  lice  a  suitable  article  of  diet,  but  since  they  do  not  come 
out  in  force  until  June,  are  a  litjtle  late  to  be  as  beneficial  as  the  mag- 
gots of  the  syrphus  fly.  The  larvse  hatch  out  from  small  yellow 
eggs.  They  have  six  legs  and  attain  a  length  of  half  an  inch,  when 
they  attach  themselves  to  a  leaf  and  in  a  little  more  than  a  week  are 
transformed  into  beetles.  The  larvae  and  beetles  both  feed  upon  the 
pea  lice,  and  consume  large  numbers. 


Fig.  33 


There  are  numerous  other  insects  which  feed  upon  the  pests,  but 
do  not  flourish  in  sufficient  numbers  to  materially  check  the  spread 
of  the  lice  where  they  have  gained  much  headway.  Among  these 
must  be  mentioned  the  lace-zvingcd  flies.  They  are  quite  green  in 
color,  the  shade  resembling  the  peas. 

The  wings  are  quite  beautiful,  being  very  thin,  showing  the  fine 
net  work  of  veins  which  break  up  the  sunlight  into  prismatic  colors. 


PEAS. 


341 


They  are  sometimes  termed  the  "golden-eyed  flies,"  because  the  eyes 
are  bright  golden  color.  The  eggs  are  deposited  on  the  leaves  singly 
on  a  stalk  of  fine  silk,  which  prevents  the  larvce  from  feeding  upon 
the  unhatched  eggs  which  they  would  surely  do.  Often  the  larger 
ones  will  feed  upon  the  weaker,  unless  sufficient  food  is  available. 
They  move  quite  freely  and  consume  large  numbers  of  lice,  grasp- 
ing them  in  their  two  curved  jaws,  then  sucking  the  fluids.  A 
single  lace-winged  fly  will  lay  about  fifty  eggs  a  day  and  the  hatched 
larvae  one  week  later  are  busy  with  the  lice. 

By  far  the  most  important  enemy  of  the  green  pea  louse  is 
fungous  disease  which  is  microscopical.  This  fungus  is  brown  mold 
called  Bntomophithora  aphidis,  and  almost  covers  the  bodies  of  the 


Plate  ion.     I^ace  Winged  Fly 
A.   adult  fly;   B.   partly  grown   larvae;   C.   pupa. 


lice.  It  enters  the  tissue,  absorbing  the  moisture,  and  causes  the 
insects  to  shrivel  up  and  die.  The  disease  is  contagious  and  spreads 
rapidly,  carrying  off  more  lice  than  all  other  enemies  combined.  It 
is  safe  to  say  that  fungoid  diseases  among  insects  are  the  means  of 
preventing  their  spread,  since  they  breed  so  very  fast  that  ordinary 
insect  enemies  could  hardly  keep  pace  with  them.  But  as  soon  as 
a  disease  breaks  out  the  organs  of  reproduction  are  deprived  of  their 
functions  and  the  check  is  generally  complete.  Some  of  these  fung- 
ous diseases  are  difficult  to  cultivate  artificially,  but  there  is  surely 


342 


CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


a  method  which  can  easily  be  discovered,  since  aU  the  conditions  nec- 
essary for  the  preparation  of  nutrient  media  are  obtainable.  This 
is  a  field  for  investigation  and  we  believe  it  both  possible  and  nec- 
essary for  research  work  to  be  done,  to  check  any  such  spread  of  in- 
sects as  was  experienced  by  growers  of  peas  in  the  three  years  so 
well  remembered  by  us  all.  This  research  work  may  be  carried  on, 
and  means  discovered  for  cultivating  the  disease  fungi  in  large  num- 
bers on  artificial  nutrient  media.  When  cultures  are  obtainable 
water  may  be  used  to  carry  the  spores  into  all  parts  of  fields  where 
the  lice  are  flourishing  and  thus  spread  disease  among  them,  which 
means  quick  extermination. 


Plate  110 

Eggs  of  Lace  Winged   Fly  and  Pea  Lice   Killed  by   Fungous   Disease. 


There  is  no  doubt  but  that  in  certain  seasons  the  weather  con- 
ditions are  such  that  disease  molds  will  not  grow  naturally,  but  if 
cultures  are  kept  in  our  laboratory  from  one  year  to  another,  we 
have  the  means  of  starting  the  disease  among  the  lice  ourselves, 
and  need  not  depend  directly  upon  nature.  There  is  considerable 
expense  connected  with  research  work  of  this  kind,  but  its  import- 
ance is  so  great  that  packers  and  those  interested  in  growing  peas 
should  take  a  lively  interest  in  lending  all  necessary  support. 


PEAS.  343 

CHEMICAL  COMPOSITION  AKD  FOOD  VALUE  OF  PEAS. 

Few  people  realize  the  great  nutritive  value  of  peas.  We  have 
mentioned  in  preceding  pages  that  peas  belong  to  the  order  of  Lcgu- 
minosac,  and  are  included  under  the  name  of  Pulses,  to  which  belong 
also  pea  beans,  and  all  other  varieties  of  beans,  lentils,  and  pea-nuts. 
These  varieties  of  food  are  extremely  rich  in  nitrogen,  which,  as 
we  have  mentioned,  is  due  to  the  absorption  of  nitrogen  from  the 
atmosphere  through  the  agency  of  minute  organisms  which  have 
the  power  of  fixing  free  nitrogen  and  reducing  it  to  nitrates,  which 
are  soluble  elements,  quickly  taken  up  by  the  plants  belonging  to  this 
group.  This  is  accomplished,  as  we  have  described,  by  bacteria 
which  form  the  nodules  on  the  roots  of  the  plants,  so  we  would  nat- 
urally expect  the  fruit  of  these  plants  to  be  veritable  "store  houses" 
of  nitrogen.  Almost  all  of  this  nitrogen  is  in  a  proteid  form,  and 
by  Church's  analyses  there  is  only  3  to  5  per  cent  of  the  total  nitro- 
gen which  is  not  in  proteid  form,  and  on  account  of  this  characteris- 
tic the  vegetables  belonging  to  family  of  pulses  have  been  named 
"the  poor  man's  beef." 

The  proteid  so  valuable  as  a  food  in  peas  is  Icguinin,  which  is 
a  casein-like  substance  resembling  the  casein  of  milk.  Sulphur  is 
a  large  ingredient  of  the  proteids  of  peas,  and  gives  rise  to  sulphur- 
etted hydrogen,  especially  when  fermentative  and  putrefactive  pro- 
cesses are  carried  on  by  bacteria.  This  gas  is  also  liberated  dur- 
ing digestive  processes,  probably  due  to  the  presence  of  putrefac- 
tive bacteria  in  the  intestines.  The  presence  of  potash  and  lime  in 
the  composition  of  peas  and  other  pulses  sometimes  causes  calcifi- 
cation of  arteries  among  strict  vegetarians. 

The  green  garden  pea  is  particularly  rich  in  carbohydrates, 
and  some  varieties  have  a  very  large  per  cent  of  sugar;  other  vari- 
eties contain  very  little,  which  has  tempted  some  canners  to  use  sac- 
charin. We  have  explained  this  custom  under  the  head  of  food 
preservatives  and  their  detection.  There  is  frequently  a  loss  of  car- 
bohydrates in  the  blanching  and  processing  of  peas,  and  the  addition 
of  granulated  sugar  really  adds  to  their  food  value. 

Since  peas  contain  so  little  fat  they  are  really  improved  by 
the  addition  of  pure  butter,  and  I  throw  out  this  hint,  which  may 
prove  valuable  to  any  packer  who  is  searching  for  specialties.  We 
all  know  that  pork  or  bacon  adds  wonderfully  to  the  taste,  flavor, 
and  nutritive  value  of  beans,  and  peas  contain  less  than  half  as  much 
fat  as  beans,  consequently  the  nutrient  value  may  be  greatly  in- 
creased by  the  addition  of  a  fatty  substance,  such  as  butter.  We 
find  that  canned  peas  heated  and  spread  with  butter  are  delicious, 
or  if  the  liquor  is  prepared  with  butter  and  pepper  and  then  poured 
over  the  peas,  they  are  very  greatly  improved  in  flavor.  The  addi- 
tion of  cream  or  milk  also  serves  the  same  purpose,  and  supplies  the 


344  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

necessary  fats  in  a  digestible  form,  a  preparation  much  esteemed  by 
many  persons.  The  addition  of  butter  to  canned  peas  before  steril- 
ization is  practicable,  because  the  same  sterilization  which  is  re- 
quired for  peas  will  also  answer  for  the  added  butter;  but  milk 
would  require  a  stronger  process,  which  would  cook  the  peas  to 
pieces,  and  the  result  would  be  something  like  pea  soup,  instead  of 
canned  peas. 

The  blanching  of  peas  before  filling  into  the  cans  is  a  most 
important  feature  of  their  preparation.  In  the  blanching  bath  the 
slimy  products  formed  by  bacteria  are  washed  away,  and  besides  this 
a  bitter  substance,  which  is  a  natural  component,  is  dissolved  and 
freed  from  the  peas.  This  bitter  principle  is  easily  detected  by  tast- 
ing a  finely  divided  raw  pea.  Just  what  it  is  I  am  unable  to  say, 
but  it  is  comparable  to  the  principle  found  in  aloes,  quassia,  and 
other  bitter  vegetables  and  barks.  The  same  bitter  principle  is  a 
common  product  of  several  species  of  bacteria,  some  of  which  have 
been  isolated  from  bitter  canned  peas.  Frequent  changing  of  the 
water  used  for  blanching  is  advisable,  because  this  bitter  principle 
is  dissolved  from  the  peas  and  although  it  is  volatile  to  some  ex- 
tent, will,  in  time  so  afifect  the  water  that  the  blanching  will  not 
be  effective. 

The  blanching  process  has  some  disadvantages,  too.  There 
seems  to  be  no  way  of  avoiding  the  loss  of  a  certain  per  cent  of  pro- 
teid  and  mineral  matter,  also  sugars,  but  the  loss  is  inconsiderable. 
There  is  more  loss  of  these  substances  from  dried  peas,  which  are 
sometimes  put  to  soak  for  several  hours.  Such  peas  are  made  up 
into  special  food  products,  the  formulae  being  proprietary. 

Of  course,  the  same  loss  is  explained  in  the  preparation  of 
"soaked  canned  peas,"  a  brand  which  should  never  be  manufac- 
tured, because  they  are  extremely  poor  in  quality  and  their  presence 
in  the  tra  le  injures  the  pea-packing  industry. 

To  show  the  composition  of  peas  in  comparison  with  some 
other  pulses  I  have  prepared  a  table  of  analyses  of  solids.  Of  course, 
the  great  bulk  of  the  raw  and  cooked  product  is  water,  which  in 
peas  amounts  to  78  to  79  per  cent,  and  in  haricots  and  scarlet  run- 
ners to  75  and  91  per  cent  respectively. 

ANALYSIS  OF  THE  SOLIDS. 

Far 

Green  Peas ;  .  .  .   2^4 

French  Beans 4 

Scarlet  Runners 3.3 

Lima  Beans 2.4 


Proteid. 

Carbo- 
hydrates. 

Cellulose. 

Mineral 
Ash. 

18 

72 

2>4 

5/3 

14 

71 

5 

6 

20 
21.6 

42 

68 

31-3 
3-6 

3-4 
4-4 

PEAS.  345 

BAIvIvAND's   ANAI^YSES. 

Beans  Lentils  Peas 

Minimum      Maximum        Minimum      Maximum       Minimum     Maximum 

Water    lo.oo       20.40       11.70       13.50       10.60       14.20 

Proteid    i3-8i       25.16       20.32       24.24       18.88       23.48 

Fat 0.98         2.46         0.58         1.45         1.22         1.40 

Starch  and  sugar5i.9i       60.98       56.07       62.45       56.21       61.10 

Cellulose    2.46         4.62         2.96       3.60         2.90         5.52 

Ash    2.38         4.20         1.99         2.66         2.26         3.50 

\\q  see  by  these  analyses  that  the  proteid  is  very  large,  also 
the  carbohydrates,  which  make  peas  of  great  nutritive  value.  About 
one  and  a  half  pounds  of  dry  peas  would  supply  the  daily  require- 
ment of  proteid  for  an  average  man,  and  the  energy  liberated, 
weight  for  weight,  is  greater  than  white  bread,  beef,  eggs  or  milk. 

The  relative  cost  of  peas  as  compared  with  these  foods  is  only 
about  one-half,  taking  as  a  standard  the  amount  of  energy  liberated, 
bread  only  being  excepted.  Now^  the  people  do  not  realize  these 
facts  and  need  education,  so  the  thought  which  suggests  itself  is 
for  the  packer  of  peas  to  advertise  them  in  such  a  w^ay  as  to  attract 
the  masses  who  are  spending  far  too  much  money  for  meat,  eggs  and 
other  foods  to  obtain  the  energy  required  for  their  existence.  If 
the  people  receive  this  information  there  is  no  doubt  that  greater 
demand  for  canned  peas  will  follow. 

There  are  great  possibilities  for  specialties  in  which  peas  may 
form  the  base.  We  have  already  mentioned  pea  soup  and  special 
combinations  with  a  sauce  containing  butter  and  seasoning,  and 
there  are,  no  doubt,  other  combinations  wdiich  may  be  tried  by  ex- 
perimenting, and  which  would  doubtless  prove  to  be  good  sellers. 
This  is  a  field  for  the  genius,  but  the  genius  usually  strikes  the  sue 
cessful  combinations  by  constant  experimental  work.  Experi- 
mental work,  let  me  say,  is  one  of  the  best  paying  investments. 
Nearly  all  of  the  most  profitable  lines  of  specialties  have  been 
worked  out  by  the  firms  who  are  constantly  experimentins:  to  ob- 
tain combinations  which  are  attractive,  both  in  price  and  quality,  and 
strange  to  say  the  popular  specialties  are  combinations  which  have 
as  a  base  some  well  known  standard  article  of  food. 

Popular  specialties  have  been  made  with  wheat,  oats,  corn, 
beans,  etc.,  combined  with  other  materials,  or  worked  up  into  modi- 
fied conditions  entirely  new,  and  they  have  become  popular  because 
they  possess  real  nutritive  value  and  are  palatable. 

There  is  too  little  experimental  work  done  by  the  canner;  he 
is  solely  occupied  with  the  idea  of  packing  a  full  crop  of  certain  pro- 
ducts, sometimes  never  dreaming  that  these  very  products  could  pos- 
sibly be  made  into  new  and  attractive  specialties,  which  might  yield 
him  two  or  three  times  the  profit  derived  from  the  regular  standard 
goods. 


346  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

By  proper  advertising  and  adhering  strictly  to  fine  quality  the 
sales  of  canned  peas  could  be  greatly  increased.  Within  a  year 
there  may  be  means  discovered  which  will  enable  the  farmers  to 
grow  peas  of  fine  flavor  and  suitable  size,  even  in  localities  where 
there  has  been  little  or  no  success  with  them  in  the  past.  We  refer 
here  to  the  means  of  inoculating  the  seed  and  soil  with  the  nitrogen 
bacteria  described  in  the  previous  pages.  When  these  experiments 
are  complete  there  will  be  more  peas  packed  and  many  factories  will 
be  able  to  pack  them,  even  in  places  which  seem  most  unfavorable. 

PI.ANTING   AND    CANNING   PEAS. 

The  old  method  of  planting  peas  in  rows  and  picking  the  pods 
by  hand,  the  pickers  having  to  go  over  the  same  vines  a  number 
of  times,  has  been  discontinued.  The  old  method  was  expensive 
and  the  results  were  not  always  as  perfect  as  the  more  modern 
methods.  Peas  are  now  sown  the  same  as  small  grain,  in  drills, 
and  there  is  appointed  a  man  of  good  judgment  who  visits  the  fields 
and  inspects  the  crops  regularly,  keeping  well  posted  on  the  progress 
shown.  He  examines  the  vines  and  when  he  finds  that  the  pods 
are  filled  with  peas  that  are  about  right  in  the  average,  he  orders 
them  to  be  cut  and  hauled  to  the  vining  machines  promptly  on 
wagons,  much  after  the  manner  of  hauling  hay  or  straw.  Of 
course,  the  planting  of  peas  is  done  at  different  times  so  that  all 
will  not  mature  at  once,  which  would  result  in  either  overworking 
the  factory  or  the  peas  would  get  too  old.  Not  all  of  the  peas  are 
fully  matured  in  a  field  ready  for  cutting,  judgment  is  exercised  and 
they  are  declared  ready  when  the  average  is  the  best,  preferably 
when  the  small  sizes  are  plentiful,  because  these  bring  the  best 
prices  and  are  sweeter  and  better  in  flavor  and  color  than  the  large 
sizes.  The  mowing  machines  are  similar  to  those  used  for  cutting 
wheat,  oats  or  hay,  and  the  vines  and  pods  are  hauled  on  wagons, 
as  we  have  said,  to  the  vining  machines,  which  should  be  near  the 
factory. 

The  vining  machines  beat  out  the  peas,  which  are  received  in 
baskets  and  then  taken  to  the  cleaners,  where  various  mechanical 
means  are  employed  to  free  them  from  dirt,  pieces  of  pods,  and 
leaves.  Usually  this  cleaning  is  done  by  means  of  a  blast  of  air 
which  blows  away  these  undesirable  things,  or  suction  is  employed 
to  hold  back  everything  excepting  the  peas  as  they  roll  over  the 
screens.  This  does  away  with  considerable  dirt  and  other  things 
and  the  peas  are  quickly  taken  to  the  grading  machines  which  are 
long  cylinders  perforated  the  entire  length,  the  holes  being  just  the 
proper  diameter  to  let  the  particular  sizes  fall  through,  first  verv 
sm.all  and  then  increasing  up  to  the  largest  size,  and  the  size  which 
cannot  go  through  any  of  the  holes  is  caught  at  the  end.     The 


PEAS.  347 

proper  grading  of  peas  is  very  important.  Great  uniformity  is  de- 
manded by  the  trade,  and  this  is  sometimes  a  difficiijt  matter  to  ac- 
comphsh,  if  the  peas  are  not  hurried  after  they  are  cut.  If  there  is 
any  shrinkage,  of  course,  peas  which  are  too  large  will  pass  in 
among  the  small  sizes  and  afterwards  will  swell,  and  spoil  the  uni- 
formity. Some  packers  divide  their  peas  into  six  or  seven  sizes, 
others  into  four  or  five,  which  is  generally  enough. 

CANNING    PEAS. 

From  the  graders  the  peas  should  be  fed  on  to  a  linen  belt, 
which  moves  slowly  past  the  girls  who  are  employed  to  pick  out  the 
imperfect  or  off-colored  peas,  also  small  pieces  of  hulls  or  leaves 
which  have  succeeded  in  passing  through  the  cleaner  and  frader. 
These  girls  should  wear  some  protection  for  their  hair,  to  avoid  the 
possibility  of  getting  any  stray  hairs  among  the  peas.  Such  an  ac- 
cident is  not  easily  forgiven  if  the  purchaser  should  be  so  unfortun- 
ate as  to  find  one.  There  should  be  a  rule  in  every  canning  factory 
stipulating  that  all  the  female  employees  wear  caps  or  some  other 
protection  for  the  hair.  Accidents  are  not  uncommon  and  the  in- 
jury done  to  the  whole  industry  is  far-reaching. 

Some  packers  prefer  to  have  the  hand-picking  done  after  the 
blanching,  because  the  blanching  brings  out  the  colors  prominently, 
and  there  may  be  some  difference  in  sizes,  too,  which  will  be  more 
apparent  after  the  peas  have  passed  through  the  water.  If  there 
are  any  which  were  shrunken  they  will,  swell  up  to  their  normal  size, 
and  if  any  of  the  yellow  seed  varieties  which  are  too  old,  the  yellow 
color  will  be  more  noticeable  after  the  blanching.  All  these  things 
which  interfere  with  perfect  uniformity,  may  be  corrected  at  this 
time. 

There  are  several  points  worthy  of  consideration  at  this  place. 
If  the  peas  are  right  in  the  beginning,  it  is  preferable  to  sort  them 
before  the  blanching,  because  it  is  wise  to  fill  them  into  the  cans  rap- 
idly after  they  have  once  been  partially  cooked,  so  it  should  always 
be  a  matter  of  prime  importance  to  see  that  the  peas  are  harvested 
in  time  and  then  put  through  the  viners  before  they  become  heated. 
The  custom  of  some  packers,  who  store  the  vines  in  sheds  and  allow 
the  lactic  acid  bacteria  and  the  spore-bearing  micro-organisms  to 
start  decomposition,  with  its  attendant  liberation  of  heat,  is  alto- 
gether wrong.  Such  peas  must  deteriorate  rapidly,  and  the  sorting 
or  picking  must  necessarily  be  done  after  the  blanching.  One 
packer  sent  me  a  number  of  samples  of  peas  taken  from  various  piles 
which  w^ere  spoiled,  the  liquor  being  muddy,  and  in  some  cases  the 
contents  were  entirely  sour.  He  states  that  his  viners  became  over- 
crowded and  it  became  necessary  for  him  to  fill  his  sheds;  the  re- 
sult was  that  they  became  heated,  necessitating  careful  sorting  after 


348  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

the  blanching  process.  There  was  considerable  delay  during  the 
sorting,  because  of  the  many  bad  peas,  pieces  of  slimy  pods  and 
leaves.  He  did  not  increase  his  process,  but  maintained  his  tem- 
perature at  a  point  just  sufficient  for  sterilizing  strictly  fresh  peas, 
and  the  result  of  it  was,  as  we  have  stated,  a  very  bad  lot  of  peas. 
Should  it  become  necessary  at  any  time  to  do  the  sorting  after  the 
blanching,  do  it  as  rapidly  as  possible,  having  a  sufficient  force  in 
order  to  avoid  the  delays  so  common. 

The  old  blanching  method  was  to  have  a  number  of  small  tanks 
iilled  with  water,  and  beside  each  a  tank  filled  with  cold  water, 
Sulphate  of  copper  was  used  by  many  to  fix  the  green  color,  and 
alum  was  used  to  toughen  the  skin  of  the  peas.  The  peas  wxre  im- 
mersed in  the  hot  water  containing  the  chemicals  mentioned  and, 
'after  about  five  minutes'  cookino-,  were  rinsed  in  the  cold  water,  then 
filled  into  cans. 

The  modern  method  is  better  because  the  chemicals  are  not 
used  and  the  blanching  is  done  automatically,  the  peas  being  carried 
through  three  baths  by  means  of  worm  conveyors,  or  spirals,  which 
are  large  enough  to  carry  the  peas  through  the  water  in  a  steady, 
regular  manner.  The  water  in  tank  No.  3  cleans  the  mucinous 
matter  from  the  peas,  and  is  attached  wn'th  the  overflow  from  tank 
No.  2.  The  second  tank  receives  the  overflow  from  No.  i,  so  all 
are  constantly  flowing,  keeping  the  water  comparatively  free  from 
dirt,  slime  and  other  matter.  After  the  blanching  a  cold  water 
spray  is  used  to  give  the  peas  firmness  and  to  prevent  them  from 
becoming  heated. 

SOUR  PKAS. 

Sour  peas  in  many  cases  are  due  to  careless  methods  before 
the  sterilizing  process,  and  a  few^  words  on  this  subject  at  this  time 
will  serve  the  packer  and  enable  him  to  avoid  the  causes.  When 
peas  get  sour  prior  to  the  sterilizing  process,  the  acidity  is  generally 
due  to  organisms  which  belong  to  the  Lactic  Acid  Group,  and  these 
germs  attack  the  carbohydrates,  converting  the  sugar  into  lactic  acid 
without  the  evolution  of  gas  sometimes.     QHij^O,,  =  2C3H6O3. 

One  molecule  sugar  =  2  molecules  lactic  acid. 

One  germ  is  rather  small,  occuring  generally  in  pairs,  some- 
times in  chains,  but  most  frequently  in  bunches  or  zooglaeae  forms. 
It  is  exceedingly  small,  measuring  only  i  to  2.8  /w-  long  and  0.3  to 
0.4  /A  wide.  Some  writers  claim  to  have  discovered  spores  in  this 
shining  species  but  the  spots  which  are  sometimes  visible  within  the 
cells.  They  are  not  true  spores  and  do  not  produce  vegetating 
forms,  so  we  call  them  spore-like  bodies,  which  are  destroyed  at 
boiling  temperature. 


of 


TV"- 


\iH\'^^ 


RS\-r^ 


of 


ii\^y 


349 


There  is  a  spore  bearing  bacillus  which  breaks  up  invert  sugar 
into  lactic  acid,  in  fact  there  is  a  large  number  of  bacteria  which 
produce  lactic  acid. 

These  germs  are  present  in  large  numbers  on  all  growling  veg- 
etables and  universally  distributed  in  air,  water  and  soil.  They 
grow  well  at  temperatures  ranging  from  lOO  to  120°  F.,  and  the 
''sweating"  so  often  seen  in  hay,  fodder,  ensilage  and  pea  vines, 
when  piled  in  heaps,  is  partly  due  to  the  lactic  acid  bacteria.  There 
are,  however,  a  number  of  bacteria  which  produce  lactic  acid,  and 
this  acid  being  quite  sour,  imparts  that  characteristic  to  any  food 
product  susceptible  to  lactic  fermentation. 


Plate  111 

Photomicrograph  of  Lactic  Acid  bacteria  which  generally  gain  entrance  to  canned  goods  through  leaks. 
These  bacteria  do  not  produce  spores  and  are  easily  destroyed  by  boiling  temperature.  Cultivated  from  cans  of 
spoiled  corn;  stained  with  carbol  fuchsine.     Magnified  1,000  diameters. 

When  pea  vines  are-piled  up  in  heaps,  the  ''sweating  process" 
begins  quite  soon,  and  within  a  few  hours  large  quantities  of  sugar 
and  starch  have  undergone  chemical  changes,  with  the  formation  of 
considerable  lactic  acid.  There  are  usually  a  number  of  organisms 
at  work  at  the  same  time.  Some  of  these  belong  to  the  class  of 
heat-loving  bacteria,  and  by  their  united  action  on  the  cellulose  and 
proteids,  the  temperature  if  often  elevated  to  120  degrees  F.,  when 
the  juices  are  freed,  and  the  so-called  "sweating  process"  is  to  be 
seen  by  overturning  the  vines. 

There  is  no  part  of  the  process  of  pea-canning  which  afifords 
so  much  danger  of  sour  goods  as. the  sweating  of  the  vines  and  pods, 
so  there  is  danger  of  allowing  the  raw  material  to  accumulate  too 


350  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


Bacillus  Butyricus,  Hueppe 

Origin.— Milk. 

Form. — Long,  narrow  rods,  having  rounded  ends;  found  frequently  in 
pairs;   may  form   threads. 

Motility. — Actively  motile. 

Sporulation. — Forms  bright  median  spores,  oval  in  shape,  at  about 
30°. 

Anilin  Dyes. — Stain  well. 

Growth. — Rapid. 

Gelatin  Plates. — The  deep  colonies  form  masses  of  a  yellowish  color, 
the  surface  colonies  liquefying  rapidly  and  then  forming  grayish-brown, 
granular  patches  having  fibrillated  borders. 

Stab  Culture. — It  liquefies  slowly  along  the  entire  line  of  inoculation. 
A  thin,  folded,  grayish-white  scum  is  formed  on  the  surface,  the  gelatin 
becoming  a  yellowish  color.  The  liquid  remains  cloudy  for  a  while,  but 
eventually  clears  up,  the  growth  settling  at  the  bottom. 

Streak  Culture. — On  agar,  a  thick,  yellow  or  grayish,  sticky  growth 
is  formed.  On  potato,"  a  light  brown,  transparent  covering  growSj  some- 
times becoming  folded. 

Milk. — The  casein  is  gradually  coagulated,  as  with  rennet.  After 
about  eight  days,  the  casein  is  redissolved  or  peptonized  with  the  forma- 
tion of  leucin,  tyrosin,  ammonia  and  bitter  products.  It  forms  butyric  acid 
from  hydrated  milk,  sugar  and  lactates. 

Oxygen  Requirements. — Aerobic. 

Temperature.— It  grows  best  at  35°  to  40°  C.  but  can  grow  at  ordinary 
temperature. 

Behavior  to  Gelatin. — Gelatin  is  liquefied  by  it. 

Aerogenesis. — It  forms  butyric  acid. 

Pathogenesis.— Y[2ls  no  effect  on  animals. 


PEAS.  351 


/ 


1. 


/ 


I  /  /• 


Plate  112.     Bacillus  Butyricus,  by  Hueppe 

Butyric  Acid  Bacteria,  showing  Flagella,  Species  isolated  f)rom  Peas  undergoing 
"sweating."  Stained  by  author's  method.  Photomicrograph  by  author.  Mag.  1,200 
diameters. 


Plate  113.     Bacillus  Butyricus,  Hueppe 

Butyric  Acid  Bacteria,  same  as  shown  in  Plate  107.  Rods  and  Spores.  Stained 
with  Cabol  Fuchsine.  Spores  are  very  resistant  to  heat.  Photomicrograph  by 
author.    Mag.  1,500  diameters. 


352  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

far  ahead  of  the  machines.  A  large  per  cent  of  the  spoilage  cases 
of  peas  investigated  in  the  laboratory  have  been  due  to  souring 
which  happened  prior  to  the  sterilizing  process.  Our  readers  will 
recall  the  great  trouble  experienced  from  sour  peas  after  the  viners 
were  first  enstalled.  I  do  not  wish  to  throw  any  reflection  whatever 
upon  the  viners,  because  I  believe  that  they  are  splendid  inventions, 
but  the  factories  were  not  properly  equipped  for  handling  peas  by 
this  system.  The  packers  in  many  cases  had  not  planned  for  the 
increased  receipts  of  raw  material,  and  the  consequence  was  that  the 
vines  were  cut  too  fast.  If  the  viners  were  operated  at  their  full 
capacity,  the  hulled  peas  would  pile  up  ahead  of  the  other  machinery, 
so  that  by  the  time  the  peas  were  finally  sealed  in  the  cans,  they  had 
undergone  marked  chemical  changes,  the  carbohydrates  or  sugars 
having  for  the  most  part  been  converted  into  lactic  acid,  and  in  some 
cases  bitter  compounds  had  formed,  together  with  butyric  and  fatty 
acids,  all  due  to  the  action  of  bacteria  of  various  species. 

One  peculiarity  of  sour  peas  is  that  it  is  impossible  to  tell  by 
the  appearance  of  the  cans  that  they  are  sour;  the  cans  appear  to 
be  all  right  and  have  the  usual  vacuum,  which  draws  in  the  ends, 
arid  do  not  swell.  Very  often  this  is  the  case,  although  not  always, 
because  souring  without  the  formation  of  gas  may  result  from  im- 
perfect sterilization;  but  in  the  great  majority  of  cases  this  takes 
place  prior  to  the  sterilizing  process. 

From  the  very  fact  that  appearance  of  sour  goods  gives  no  in- 
dication of  the  trouble,  the  cans  may  be  scattered  throughout  the 
piles  and  cause  a  great  deal  of  dissatisfaction  when  they  reach  the 
trade.  The  question  is  frequently  asked :  "How  will  I  be  able  to 
pick  out  the  sour  cans  so  that  I  may  avoid  trouble  with  the  trade?" 
I  will  give  you  a  few  practical  hints  which  may  serve  you,  should 
you  be  so  unfortunate  as  to  permit  your  goods  to  get  sour.  Nearly 
all  fatty  acids  are  volatile  to  some  extent,  and  if  heated  pass  into 
a  gaseous  state,  although  not  completely,  and  after  cooling  will 
again  become  liquid,  but  sometimes  quite  slowly :  now  we  can  take 
advantage  of  this  physiological  characteristic  and  heat  our  cans  in 
boiling  water  until  the  ends  of  all  are  swelled,  then  by  applying  cold 
water  the  cans  whose  ends  draw  in  rapidly  are  good,  while  those 
whose  ends  draw  in  slowly  are  probably  all  sour.  To  do  this  ex- 
peditiously, place  the  cans  in  crates  which  hold  onl}^  a  single  row  of 
cans,  then  turn  the  bottoms  upward,  then  lower  into  open  bath  of 
boiling  water  and  heat  until  the  ends  of  all  the  cans  swell  completely. 
Do  not  heat  long  enough  to  cook  the  peas,  because  the  tender  peas 
may  become  too  soft  and  dissolve  in  the  liquor,  thus  making  it  tur- 
bid or  cloudy.  After  the  ends  are  all  swelled,  lift  the  crate  from  the 
boiling  water  into  a  tank  of  cold  running  water,  just  deep  enough  to 
be  entirely  submerged.     In  a  short  time  the  ends  of  the  good  cans 


PEAS.  353 

will  respond  to  the  vacuum  produced,  and  will  snap  back,  while 
those  cans  which  contain  volatile  or  fatty  acids  will  remain  swelled 
for  perhaps  thirty  minutes  to  one  hour.  Of  course  some  good  cans 
will  not  draw  in  rapidly,  especiall}^  if  they  had  been  somewhat  chilled 
before  sealing;  the  vacuum  in  this  case  would  be  quite  weak  and 
of  course  would  not  respond  quickly  to  the  chilling,  in  the  process 
previously  described.  It  is  not  always  possible,  therefore,  to  save 
every  good  can  by  this  method,  but  if  due  care  and  judgment  are 
exercised,  all  sour  cans  may  be  detected  and  removed.  Sour  peas 
cannot  be  made  good.     They  are  a  loss  and  should  be  dumped. 

The  "sweating"  previously  described  is  not  the  only  source  of 
sour  peas.  There  is  no  stage  of  the  process  where  delays  are  so 
dangerous  as  after  the  blanching.  Bacteria  as  a  rule  are  true  scav- 
engers and  invade  partially  cooked  material  rapidly.  The  cooking 
which  the  peas  received  in  the  blanching  is  attended  with  a  certain 
loss  of  carbohydrates  and  proteid, ,  and  the  liberation  of  natural 
juices  and  softening  of  cellulose,  so  they  afford  a  rich  soil  for  the 
development  of  bacteria.  Furthermore,  the  heating  softened  the 
spores  of  the  heat-resisting  bacteria,  which  rapidly  develop  into 
vegetating  rods,  forms  which  produce  the  remarkable  changes  so 
often  noticed  in  canned  goods. 

During  any  of  the  delays  occuring  after  the  blanching,  the 
danger  of  souring  is  great,  so  it  is  always  preferable  to  do  the  sort- 
ing prior  to  the  blanching.  Delays  sometimes  happen  where  the 
peas  are  filled  into  cans,  and  at  the  capping  machines,  where  great 
stacks  of  cans  are  piled  up.  Like  all  automatic  devices,  these  ma- 
chines sometimes  get  out  of  order,  and  considerable  time  is  lost 
making  changes  or  repairs,  so  it  is  advisable  to  have  extra  machines 
to  avoid  the  delays  as  much  as  possible,  in  order  to  prevent  souring 
of  the  peas  at  these  times. 

The  blanching  of  peas  should  vary  in  length  of  time  according 
to  size,  the  small  peas  should  receive  less  cooking  than  the  large 
sizes,  the  time  varying  from  five  to  ten  minutes. 

vSome  successful  packers  use  alum  in  the  blanching  to  harden 
the  skin  of  the  peas,  and  I  do  not  see  any  objection  to  it.  It  is 
hardly  likely  that  the  employment  of  alum  for  this  purpose  would 
be  condemned  by  food  commissioners  as  illegal,  and  while  its  em- 
ployment is  not  absolutely  necessary,  nevertheless  it  does  prevent 
the  cracking  of  the  skins,  and  will  insure  a  much  clearer  liquor  for 
that  reason. 

The  filling  of  peas  into  the  cans  was  formerly  done  by  hand  by 
the  aid  of  small  funnels,  and  the  perfection  of  automatic  devices  for 
Recently,  machinery  for  this  purpose  has  been  made  which  accom- 
plishes the  filling  with  great  uniformity,  giving  better  average  re- 
sults than  hand  filling.  One  bushel  of  peas  fills  about  fifteen  No.  2 
cans,  approximately. 


354  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

The  filling  of  peas  into  the  cans  is  important;  the  cans  must 
open  up  full,  but  care  must  be  taken  not  to  fill  them  too-  full  because 
the  peas  will  crack  open  in  the  sterilizing  process. 

After  the  cans  are  filled  with  peas,  enough  weak  brine  is  added 
to  cover  them.  The  brine  may  be  filled  by  machinery — an  attach- 
ment for  this  purpose  is  usually  connected  with  the  pea  filler.  The 
brine  is  made  by  dissolving  about  six  pounds  of  salt  in  forty  gal- 
lons of  water.  Some  packers  use  a  small  quantity  of  saccharin  to 
sweeten  the  peas.  Eight  pounds  of  granulated  sugar  added  to  the 
brine  gives  splendid  results. 

The  brine  should  be  made  quite  clear,  and  where  filtered  water 
is  available  it  is  to  be  preferred,  although  well  or  spring  water  is 
very  good.  The  water  used  for  all  canned  goods  should  be  pure 
and  clear,  surface  water  and  the  muddy  water  so  often  seen  in  large 
cities,  which  obtain  their  supply  from  rivers,  is  not  desirable,  unless 
properly  filtered.  Water  which  may  be  contaminated  from  sewage 
or  decomposing  vegetable  matter,  so  often  seen  in  the  vicinity  of 
canning  factories,  should  not  be  used,  because  it  may  contain  pro- 
ducts elaborated  by  bacteria  which  may  injure  canned  goods.  Much 
of  the  salt  sold  on  the  market  is  impure,  containing  much  foreign 
matter,  so  it  is  advisable  to  pay  a  little  riiore  and  obtain  the  refined 
table  salt,  which  with  pure  water  ought  to  give  a  clear  brine. 
Granulated  sugar  is  to  be  preferred  to  ordinary  light  brown  sugars, 
because  it  will  stand  the  process  without  any  burnt  sugar  flavor. 
During  some  seasons,  and  in  some  localities,  the  peas  are  sufficiently 
sweet  without  the  addition  of  sugar,  but  ordinarily  a  little  sugar 
adds  greatly  to  the  quality  of  peas. 

MUDDY   LIQUOR. 

Muddy  liquor  is  so  often  the  occasion  of  losses  that  I  will  ex- 
plain some  of  the  causes  which  have  come  to  my  notice.  The  phe- 
nomenon is  usually  noticeable  a  few  days  after  processing;  in  some 
cases  it  is  seen  as  soon  as  the  cans  are  processed.  If  we  examine 
the  peas  which  have  stood  for  some  time  before  blanching,  we  will 
notice  that  they  are  quite  sticky.  This  viscid  matter  is  due  to  the 
action  of  bacteria,  and  is  the  product  formed  by  the  growth  of  the 
germs  on  the  carbohydrates  and  proteids.  One  of  the  principle 
agents  is  Bacillus  mesentericus  vulgatus,  an  organism  first  found 
on  potatoes,  for  which  reason  it  is  sometimes  called  the  "potato  ba- 
cillus." It  is,  however,  a  widespread  variety  and  is  present  in 
water,  soil,  and  on  the  leaves,  pods,  stems  and  roots  of  nearly  all 
vegetables. 

Bacillus  mesentericus  vulgatus  is  a  thick  bacillus,  measuring 
from  V2  />«•  to  3.5  i"-  in  length,  straight,  with  ends  somewhat  round, 
actively  motile  when  young,  due  to  numerous  flagella  which  grow 


PEAS.  355 


',- 


1 


-    3     _ 

Plate  114.     Bacillus  Mesentericus  Vulgatus,  Flagellated 

Photomicrograph  of  Bacillus  Mesentericus  Vulgatus:  Isolated  from  slimy  peas; 
cause  of  muddy  liquor  in  canned  peas.  Bacilli  showing  numerous  flagella,  stained 
by  Duckwall's  method.     Magnified  1,200  diameters. 

all  over  the  surface.  It  grows  singly,  often  in  pairs  and  short 
chains,,  and  soon  gives  rise  to  spores  which  are  quite  resistant  to 
heat.  When  cultivated  on  agar,  the  colonies  are  at  first  almost 
transparent,  becoming  bluish  white  and  gradually  extend,  growing 


^       •"'S  Ji**  "*^V  '^'t 


Plate  115 

Photomicrograph  of  Bacillus  Mesentericus  Vulgatus,  showing  rods  and  spores. 
Taken  from  Agar  culture  and  stained  with  fuchsine.  Spores  are  very  resistant 
to  heat.      Found   in  slimy  peas.     Magnified  1,500   diameters. 


356  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

more  opaque  and  wrinkled.  The  streak  culture  is  a  dirty  white,  and 
spreads  rapidly  over  the  whole  surface,  forming  slime  rapidly.  On 
gelatin  the  growth  is  rapid,  and  liquefaction  takes  place  along  the 
entire  line.  It  is  aerobic  and  facultative  anaerobic  and  grows  well 
at  room  temperature,  but  most  rapidly  at  loo  to  105°  F.,  in  which 
temperatures  it  forms  spores  very  fast,  and  these  are  located  near 
the  center  of  the  rods.  After  spores  begin  to  form,  the  cells  slowly 
dissolve  into  a  slimy  mass  cementing  the  surrounding  spores  to- 
gether. We  have  succeeded  in  photographing  them  thus  as  indi- 
cated in  plate  46. 

The  slime  produced  by  this  organism  is  so  mucinous  that  it 
may  be  drawn  out  into  long  threads  by  dipping  the  platinum  loop 
into  a  growth  on  agar. 

As  may  be  imagined  by  our  readers,  it  is  quite  difficult  to  ob- 
tain a  slide  preparation  sufBciently  free  from  slime  to  demonstrate 
by  staining  the  flagella  or  organs  of  locomotion  as  shown  in  plate 


Plate  116.     Butyric  Acid  Bacillus,  Flagellated 

Photomicrograph  of  a  Butyric  Acid  Bacillus  which  softens  cellulose.  Isolated 
from  peas  during  "sweating."  Cause  of  souring  and  clouded  liquor.  Bacilli  show- 
ing numerous  flagella.     Stained  by  Duckwall's  method.    Magnified  1,200  diameters. 

114;  but  it  may  be  done  by  inoculating  a  test  tube  of  bouillon,  and 
after  a  growth  is  obtained,  the  surface  of  agar  is  streaked  with 
a  small  platinum  loopful  of  the  culture.  Within  six  hours  a  thin, 
almost  transparent  film  will  be  seen  to  be  extending  over  the  sur- 
face, and  from  the  edge  of  this  a  growth  of  the  bacilli  sufficiently 
young  and  free  from  slime  may  be  obtained  for  the  demonstration 
of  flagella. 


PEAS.  357 

When  the  mucinous  matter  forms  on  the  peas,  it  cannot  be 
entirely  removed  in  the  blanching  bath,  because  the  cellulose  or 
fibre  has  been  softened  and  the  bacteria  have  gained  entrance  to 
the  interior,  so  during  the  final  processing  this  matter,  together 
with  the  mealy  substance  of  the  peas,  is  diffused  throughout  the 
liquor  which,  of  course,  gives  it  a  muddy  appearance. 

As  we  have  explained  in  previous  pages,  the  sweating  pro- 
cesses either  among  the  vines  or  shelled  peas  are  the  chief  causes  of 
souring,  so  also  they  are  the  chief  causes  of  muddy  liquor. 

There  is  another  bacillus  which  produces  butyric  acid,  and  is 
strictly  anaerobic,  which  condition  is  produced  in  the  center  of 
heated  vines  and  peas,  the  oxygen  being  all  utilized  by  the  bacteria 
on  the  surface  of  the  mass.  This  organism  resembles  bacillus 
butyricus  amylobacter,  but  seems  to  differ  from  it  in  spore  for- 
mation. It  is  actively  motile  in  the  vegetative  state,  having  num- 
erous flagella. 


Plate  117 

Photomicrograph  of  a  Butyric  Acid  Bacillus  which  produces  terminal  spores. 
Isolated  from  peas  during  "sweating."  Cultivated  by  Pyrogallate  method,  stained 
with  fuchsine.     Magnified  1,000  diameters. 

I  found  this  bacillus  in  the  central  portions  of  a  basket  of 
shelled  peas  which  had  stood  over  night.  There  was  a  perceptible 
odor  of  normal  butyric  acid,  and  the  peas  were  quite  hot  and  slimy. 
The  organism  did  not  grow  in  the  Petri  dishes,  so  I  inoculated  a 
small  test  tube,  and  tried  the  pyrogallate  method,  described  in 
Chapter  III,  for  the  cultivation  of  anaerobic  bacteria.  The  organ- 
ism grew  quite  well,  and  is  about  2  fi  long  and  9.7  />i  in  breadth, 
giving  rise  to  terminal  spores    very    much    resembling    Bacillus 


358  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

Tetani,  which  is  the  cause  of  lockjaw,  described  in  Chap.  II.  (See 
Plate  27.)  The  spores  were  not  so  near  the  end  of  the  rods,  how- 
ever, some  being  near  the  center,  but  generally  pretty  close  to  the 
end.     See  Plate  48. 

This  organism  rapidly  softened  the  cellulose  and  the  skins  of 
the  peas  became  quite  soft.  I  used  the  utmost  care  in  blanching, 
and  filled  the  cans  with  filtered  brine,  but  after  the  sterilizing  pro- 
cess the  liquor  was  very  muddy  and  viscid.  The  inside  of  the  peas 
was  soft  and  became  diffused  throughout  the  contents  of  the  cans, 
so  I  had  pretty  good  evidence  that  the  bacillus  in  question  was  the 
cause.  Frankel  and  Pfeififer  isolated  an  organism  very  similar  to 
this  from  a  rotten  melon,  and  Omelianski  describes  an  anaerobic 
bacillus  having  terminal  spores  which  softened  cellulose,  produced 
butyric  acid,  carbonic  acid  and  hydrogen  corresponding  closely  to 
this  organism  found  in  the  peas. 

There  are  other  varieties  seen  in  bacteriological  examinations, 
which  produce  changes  of  this  kind,  set  free  volatile  and  fatty  acids, 
and  impart  unpleasant  flavors  to  peas  which  are  allowed  to  stand 
exposed,  so  we  call  particular  attention  to  the  necessity  of  quick 
work  between  the  cutting  of  the  vines,  and  the  sterilizing  process. 

Another  cause  of  muddy  liquor  in  cans  of  peas  is  due  to  over- 
filling the  cans  with  peas.  We  should  always  bear  in  mind  that 
peas  swell  some  during  sterilization,  and  if  filled  too  closely  will 
pack  and  this  causes  the  skins  to  burst,  permitting  the  mealy  parts 
of  the  peas  to  become  diffused  throughout  the  contents.  This  is 
a  feature  of  pea  packing  not  generally  known  among  canners,  so 
I  desire  to  call  particular  attention  to  the  fact  that  the  cans  must 
not  be  filled  too  full  of  peas.  This  difficulty  is  obviated  by  the 
employment  of  modern  filling  machines  and  is  not  so  common  as  it 
was  in  the  days  of  hand  filling.  The  measures  in  the  machines 
should  be  set  to  hold  just  enough  peas,  so  that  the  cans  will  be 
filled  up  to  three-quarters  of  an  inch  from  the  top. 

Overprocessing  is  another  cause  of  muddy  or  cloudy  liquor. 
If  the  peas  are  cooked  to  pieces,  of  course,  the  liquor  will  not  be 
clear.  To  properly  sterilize  the  peas  without  cooking  them  to 
pieces  requires  more  judgment  than  any  other  step  in  the  process 
of  pea  packing.  There  are  so  many  sizes,  all  requiring  different 
time,  and  the  nature  of  the  peas  must  also  be  taken  into  considera- 
tion— some  varieties  requiring  longer  time  than  others. 

Another  cause  of  clouded  liquor  is  imperfect  sterilization,  and 
by  that  I  mean  that  all  bacteria  are  not  destroyed.  There  are 
some  bacteria  which  have  spores  of  great  resisting  powers  against 
heat,  and  if  they  are  not  destroyed  will  develop  in  the  cans  where 
the  sterilizing  process  is  insufficient.  Swelled  cans  usually  result, 
but  there  are  some  varieties  of  bacteria  which  do  not  produce  gas 


PEAS.  359 

when  growing  in  some  substances  and  canned  peas  seem  to  favor 
this  phenomenal  characteristic. 

As  a  rule  these  bacteria  produce  volatile  and  fatty  acids  which 
expand  when  the  cans  are  heated,  but  at  ordinary  temperatures 
there  is  no  outward  indication  that  the  contents  have  undergone 
chemical  changes.  vSuch  cans  of  peas  are  sour,  of  course,  and  the 
liquor  is  clouded,  because  it  is  the  culture  medium  for  these  bac- 
teria. Sour  peas,  due  to  imperfect  sterilization,  are  exceptional, 
because,  as  I  have  said,  the  cans  more  often  swxll ;  but  I  have  seen 
a  few  cases. 

When  the  sterilization  process  is  not  complete,  it  generally 
happens  that  swells  result,  but  this  is  not  always  the  case.  There 
are  a  number  of  bacteria  which  may  cause  souring  without  the  gen- 


Plate  118.     Bacillus  Megatherium 

Photomicrograph  and  Slide  Preparation  by  the  Author.  Bacilli  growing  in 
chains,  vegetating  forms  showing  segmentation.  Culture  isolated  from  can  of 
sour  peas.    Stained  with  tannic  acid  and  gentian  violet.     Magnified  1,000  diameters. 

eration  of  any  gas.  Some  bacteria  which  produce  gas  when  grow- 
ing in  some  goods  do  not  produce  it  when  growing  in  other  goods. 

The  anaerobic  bacteria  generally  produce  much  gas,  and  the 
extremely  foul  odors  present  in  swelled  cans  of  peas  are  ordinarily 
due  to  them,  while  the  souring  is  more  frequently  caused  by  germs 
which  are  aerobic  and  facultative  anaerobic.  vSome  of  these,  how- 
ever, form  sulphuretted  hydrogen  which  has  a  very  unpleasant 
odor. 

When  sterilization  is  incomplete  the  spores  are  not  killed  and 
after  a  short  time  they  begin  to  vegetate,  utilizing  elements  neces- 
sary for  their  growth — viz.,  carbon,  oxygen,  nitrogen,  hydrogen, 


360  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


Plate  119.     Bacillus  Megatherium 

Showing  Flagella  from  Agar  culture,  eight  hours'  growth.  Bacilli  isolated 
from  can  of  sour  peas,  showing  much  slime  in  the  liquor.  Photomicrograph  and 
slide  preparation  by  the  author.  Flagella  stained  by  special  method.  Magnifiec' 
1,200  diameters. 

etc.,  and  these  elements  are  obtained  by  breaking  up  the  molecules 
containing-  them,  causing  marked  chemical  changes  most  noticeable 
in  the  sugar  or  carbohydrates.  The  sugar  is  broken  up  and  there 
are  formed  various  acids  or  alkalies  according  to  the  nature  of  the 
organisms  at  work. 

Lactic  acid  is  found  by  a  large  number  of  bacteria,  and  this 
is  one  of  the  chief  products  which  gives  peas  a  very  sour  taste.     In 


Plate  120.     Bacillus  Megallierium 

Showing  spores  free  and  forming  in  the  rods.  Forty-eight-hour  culture  on  Agar 
obtained  by  plate  method  from  can  of  slimy  sour  peas.  Photomicrograph  and 
slide  preparation  by  the  author.    Stained  with  fuchsine.    Magnified  1,200  diameters. 


PEAS.  361 

nearly  all  cases  of  souring  the  liquor  becomes  quite  muddy,  often 
viscous.  Slime  is  formed  by  several  species  belonging  to  the  well- 
known  aerobic  spore-bearing  bacteria.  I  have  seen  the  liquor  on 
canned  peas  so  slimy  that  threads  more  than  a  yard  long  could  be 
drawn  out  of  the  cans  by  dipping  a  platinum  wire  into  the  juice  and 
slowly  drawing  it  out.  The  organism  at  work  in  this  case  was 
Bacillus  Megatherium. 

This  organism  was  first  discovered  by  De  Bary  on  boiled  cab- 
bage, but  is  quite  common  and  widespread  on  various  vegetables. 
It  is  a  bacillus  having  round  ends,  quite  large,  being  5  to  6  /^  long 
and  about  2.5  /*  thick.  It  forms  chains  of  several  members,  and 
when  stained  in  a  certain  way  may  show  segments  (see  Plate  118) 
or  division  lines,  so  that  a  single  bacillus  will  appear  to  be  composed 
of  three  or  four  members,  which  is  indeed  the  case,  each  one  hav- 
ing the  power  to  grow  out  into  the  long  form  so  that  a  chain  will 
result,  looking  something  like  sausages.  When  forming  spores 
the  cells  are  nearly  filled  (see  plate  120)  and  the  cell  seems  to  dis- 
solve away,  leaving  a  somewhat  smaller  spore  than  we  would  ex- 
pect to  see.  These  spores  are  quite  resistant  to  heat  and  are  able 
to  stand  boiling  for  some  time.  The  special  character  of  megath- 
erium is  that  it  is  slowly  motile,  although  possessing  numerous 
flagella,  produces  cloudiness  and  slime,  forms  abundant  sulphur- 
etted hydrogen,  has  no  indol  reaction  and  forms  spores  rapidly. 

The  peas  which  contained  this  organism  had  been  processed 
for  25  minutes  at  240°  F.  Many  of  the  cans  were  swelled  and  in 
some  of  these  I  found  the  butyric  acid  bacteria  described  in  previous 
pages.  Another  case  of  sour  peas  caused  by  insufficient  steriliza- 
tion came  to  my  notice  some  time  ago  when  the  party  had  filled 
his  retorts  with  water  to  a  certain  height  and  then  attempted  to 
process  them  with  a  steam  supply  at  the  top  (instead  of  the  bottom) 
of  the  retorts.  Of  course,  all  the  peas  below  the  surface  of  the 
water  soured,  and  the  most  of  them  swelled.  One  peculiar  feature 
of  this  case  was  a  complete  bleaching  out  of  all  the  natural  color  of 
the  peas ;  the  chlorophyl  had  succumbed  to  the  sulphur  gas  formed 
in  the  can.  This  gas  had  been  generated  by  a  certain  species  of 
anaerobic  bacteria. 

In  the  sour  peas,  of  wdiich  there  were  quite  a  number,  I  iso- 
lated one  which  had  produced  considerable  formic  acid,  also  a 
slight  per  cent  succinic  acid.  This  organism  was  quite  motile  and 
did  not  form  spores.  It  had  numerous  flagella  and  when  grown  on 
the  surface  of  nutrient  agar  produced  a  beautiful  red  color.  This 
was  bacillus  prodigiosus  and  under  certain  conditions  grows  won- 
derfully, sometimes  giving  off  the  odor  of  herring  brine.  It  does 
not  form  spores,  as  we  have  said,  consequently  is  easily  destroyed. 
The  process,  therefore,  was  very  ineffective  where  this  can  had 


362  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

stood  in  the  retort.  The  can  must  have  been  among  those  at  the 
bottom.  We  have  described  this  organism  pretty  fully  under  the 
head  of  chromogenic  bacteria,  chapter  II. 

One  can  which  I  examined  showed  a  very  clouded  liquor,  but 
was  not  so  slimy.  The  peas  in  this  can  were  quite  firm  and  had 
a  rather  raw  taste,  due  to  insufficient  cooking.  An  examination  of 
the  liquor  showed  the  presence  of  ver}^  motile  bacteria,  some  of 
which  were  extremely  long.  Even  the  longest  of  them  had  a  ser- 
pentine motion,  so  I  made  inoculations  in  agar  and  put  the  dishes 
in  the  incubator  for  development  of  colonies. 


Plate  121 .     Bacillus  Prodigiosus 

Photomicrograph  and  slide  preparation  by  the  author.  The  staining  was  done 
by  special  method  for  the  demonstration  of  flagella.  This  organism  was  isolated 
from  a  can  of  sour  peas.  On  Agar  produces  a  beautiful  red  color  or  pigment. 
The  bacillus  is  sometimes  called  Monas  Prodigiosus  and  "Bleading  Bread,"  be- 
cause it   forms   red   spots   on   bread.     Magnified   1,000   diameters. 

On  the  following  day  small,  irregular,  shining  white  colonies 
made  their  appearance  and  grew  rapidly,  sending  out  little  hair-like 
threads  in  all  directions,  visible  when  magnified  about  fifty  times. 
A  thin,  almost  transparent  bluish  film  soon  spread  rapidly  to  the 
walls  of  the  dish.  From  the  edge  of  this  film  I  obtained  a  speci- 
men for  staining  flagella.  The  organism  has  all  the  characteristics 
of  Bacillus  Subtilis,  or  the  Hay  Bacillus. 

After  two  days  the  culture  began  forming  spores  which  are 
located  near  the  center  of  the  rods.  These  spores,  when  inocu- 
lated into  good  cans  of  peas,  produced  the  same  cloudiness  seen  in 
the  original  can  from  which  the  colonies  were  isolated.  The  spores 
are  quite  large  and  seem  to  have  a  very  thick  membranous  wall,  as 
shown  in  the  plate.     The  walls  of  the  spores  take  the  stain  well, 


PEAS.  363 

while  the  center  of  the  spores  remains  nncolored.  The  dye  is  not 
able  to  penetrate  to  the  center,  although  heated  for  some  time  di- 
rectly over  a  flame  until  steam  arose  from  the  cover  glass.  This 
organism  and  those  similar  to  it  are  among  the  great  heat-resist- 
ing bacteria,  requiring  fully  ten  minutes'  exposure  to  250°  F.  be- 
fore being  devitalized. 

The  question  is  often  asked,  "How  long  shall  I  process  my 
peas  so  they  will  keep?"  This  cannot  be  answered  in  a  manner  to 
cover  all  conditions  and  sizes,  but  we  can  give  the  results  of  quite 
a  number  of  experiments  to  demonstrate  the  effect  of  certain  tem- 
peratures on  peas  which  were  put  through  rapidly  from  the  time 
the  vines  were  cut  until  they  were  put  into  the  retorts  for  steriliza- 
tion. I  made  a  number  of  experiments  with  peas,  canned  in  the 
manner  often  seen  in  canning  houses,  where  the  vines  were  allowed 
to  become  heated.  In  the  latter  case  the  sterilization  seemed  to  be 
more  effective  than  peas  put  through  quickly,  but  muddy  liquor  re- 
sulted in  a  number  of  cans,  showing  that  the  cellulose  had  become 
much  softened.  I  attribute  the  more  complete  sterilization  to  the 
fact  that  all  spores  were  probably  giving  rise  to  vegetating  rods 
which  are  easily  destroyed  by  boiling  temperature.  Many  cans 
were  sterilized  completely  in  twelve  minutes  at  240°.  The  cans 
were  placed  in  an  incubator,  where  the  temperature  was  maintained 
at  blood  heat,  'which  is  favorable  for  the  growth  of  most  bacteria. 
Out  of  twelve  cans  processed  at  the  temperature  given  above  only 
two  swelled  and  the  balance  kept  all  right.  I  opened  them  after 
several  months,  and  although  the  liquor  was  clouded,  the  peas  were 
not  undergoing  decomposition;  the  bacteria  were  all  destroyed. 
If  any  spores  had  been  present  before  the  sterilizing  process  the 
temperature  and  time  of  exposure  would  have  been  insufficient  to 
destroy  them.  In  order  to  demonstrate  that  all  bacteria  in  these 
cans  were  dead  after  sterilization,  I  streaked  a  number  of  Petri 
dishes  containing  nutrient  agar  with  the  juice  of  the  peas,  then 
placed  them  in  the  incubator  in  a  temperature  of  98°  F.,  where 
they  remained  until  the  agar  dried  up,  without  showing  any  signs 
of  bacterial  growth. 

After  this  experiment  I  tried  a  number  of  cans  of  very  small 
peas  taken  from  the  vines  as  quickly  as  possible,  and  covered  them 
with  good  clear  brine  and  then  processed  them  for  12  minutes  at 
240°  F.,  the  same  as  I  had  given  the  cans  in  the  previous  experi- 
ment'. In  two  days  all  of  these  cans  swelled  in  the  incubator  and 
I  removed  them.  The  pressure  from  the  gas  generated  within  the 
cans  was  great  and  when  punctured  the  juice  squirted  out  with 
considerable  force.  An  examination  of  this  juice  by  the  hanging 
drop  method  revealed  a  number  of  rod  forms  showing  motility. 
There  were  several   kinds,   some  of  them   quite  active,   spinning, 


364  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


Bacillus  Subtilis,  Ehrenbergf 

HAY  BACCLLUS. 

Origin.- — In  water,  soil,  faeces,  putrid  fluids  and  in  infusions  of  hay. 

Form. — Large,  rather  thick  rods,  having  rounded  ends  and  being  three 
to  four  times  as  long  as  wide.  Found  usually  in  pairs ;  frequently  in 
threads. 

Motility. — Actively  motile ;  snake-like  motion ;  having  from  eight  to 
twelve  flagella. 

Sporulation. — Large,  oval  spores  are  formed  at  or  near  the  middle, 
without  enlargement;  these  are  highly  resistant,  and  may  be  double  stained 
readily.     Germination. 

Anilin  Dyes. — Stain  readily,   as   does  Gram's  method  also. 

Growth. — This  is  very  rapid ;  cell  division  has  been  observed  to  take 
place  in  seventy-five  minutes  at  21°  and  in  twenty  minutes  at  35°. 

Gelatin  Plates. — The  surface  colonies  liquefy  gelatin  rapidly  and  ex- 
tensively. The  central  portion  of  the  colony  presents  the  appearance  of 
a  grayish-yellow,  irregular  mass ;  on  close  examination  it  is  seen  to  be 
made  up  of  moving  cells.  This  is  surrounded  by  a  lighter,  granular  zone. 
The  border  is  quite  characteristic,  consisting  of  a  dense  zone  of  bacilli 
and  threads,  radially  arranged,  the  ends  projecting  outward,  presenting  a 
striking  appearance — the  so-called  "ray  crown." 

Stah  Culture. — Funnel-shaped  liquefaction  takes  place  very  rapidly 
along  the  entire  line  of  inoculation.  White,  flocculent  niasses  accumulate 
at  the  bottom,  the  liquid  above,  which  is  at  first  turbid,  becoming  clear. 
A  dense  white  scum  or  zooglea  is  usually  formed  on  the  surface. 

Streak  Culture. — On  agar,  a  dull  grayish-white,  thick,  folded  scum  is 
formed.  It  develops  well  on  potato,  forming  a  moist,  thick,  yellowish 
white  covering,  at  first  velvety  in  appearance,  but  later  becoming  dry  and 
granular,  which  contains  spores  as  well  as  involution  forms.  On  blood- 
serum  it  forms  a  folded  scum  and  liquefies. 

Oxygen  Requirements. — Aerobic. 

Temperature. — It  will  grow  at  from  10°  to  45**  C.  Best  at  about  30°  C. 

Behavior   to   Gellatin. — Liquefies   rapidly  and   extensively. 

Pathogenesis. — It  has  no  effect.  If  spores  are  injected  into  the  blood 
they  soon  disappear,  being  taken  up  by  the  liver  and  spleen.  They  may 
preserve  their  vitality  after  being  stored  up  in  these  organs  for  sixty  to 
seventv   days.     (Wyssokowitsch.) 

A  large  number  of  bacilli  resemble  to  a  marked  extent  the  Bacillus 
subtilis.     It  is,  therefore,  customary  to  speak  of  the  group  of  hay  bacilli. 


PEAS. 


365 


Plate  122.     Bacillus  Subtilis 

Vegetating  rods  from  a  very  young  culture  on  Agar.     Bacilli  showing  flagelh 
Magnified  1,000  diameters. 


Plate  123.     Bacillus  Subtilis  and  Spores 

Photomicrograph  and  slide  preparation  by  the  author.  The  spores  have  very 
thick  cell  membrane  almost  impenetrable  by  heat.  This  germ  is  also  called  the 
hay  bacillus,  having  been  found  first  in  hay.  This  specimen  was  obtained  from 
can  of  sour  peas  having  cloudy  liquor.  Isolated  by  plate  culture  in  Agar.  Mag- 
nified 1,000  diameters. 


366  CANNING  AND  PRESERVING  OP  FOOD  PRODUCTS. 

turning  over  and  over  in  somersaults ;  some  were  slower  in  motion, 
having-  a  tendency  to  stand  on  end  and  to  collect  in  bunches  near  the 
center  of  the  drop  of  juice.  These  were  the  anaerobic  species 
which  do  not  thrive  in  the  presence  of  oxygen. 

The  activity  motile  rods  belonged  to  the  aerobic  species  and  are 
able  to  live  also  in  an  anaerobic  condition.  I  isolated  the  various 
forms,  some  of  which  would  not  grow  at  all  on  the  surface  of  the 
Petri  dishes.  The  anaerobic  species  developed  well  in  test  tubes 
containing  agar  by  making  the  inoculation  w^ith  a  platinum  needle 
plunged  clear  to  the  bottom.  These  tubes  were  placed  in  the  an- 
aerobic culture  apparatus,  where  all  oxygen  is  replaced  by  hydrogen 
or  absorbed  by  neutralized  pyrogallic  acid.  (See  Chapter  III.) 
I  made  some  experiments  with  the  self-registering  thermometer 
to  ascertain  how  long  a  time  was  required  for  the  temperature  in- 


Plate  124.     Anaerobic  Bacillus  from  Peas 

Vegetating  rods  from  a  culture  grown  by  Pyrogallate  method  in  a  stab  cul- 
ture in  Agar.  Flagella  very  much  curled  and  twisted,  giving  rapid  motility  to 
the  cells.  Staining  done  by  author's  special  method.  Photomicrograph  with  ace- 
tylene light  by  the  author.  Isolated  from  swelled  can  of  very  young  peas.  Mag- 
nification,  1,200  diameters. 

dicated  on  the  retort  thermometer  to  register  at  the  center  of  cans 
of  peas.  The  self-registering  thermometers  are  made  in  two  ways. 
One  is  made  to  fit  a  can  specially  constructed  for  the  purpose ;  it  is 
screwed  downward  from  the  top  and  is  sealed  with  a  gasket,  the 
mercury  column  being  exactly  in  the  center  of  the  can.  The  other 
kind  rests  on  a  tripod,  which  may  be  inserted  into  the  regular  can 
and  held  in  position  by  the  legs  of  the  stand.  The  first  kind  is  not 
suitable  from  the  fact  that  the  gasket  frequently  leaks,  and  there  is 
more  metal  used  in  constructing  the  special  can,  thus  preventing  the 
heat  from  penetrating  to  the  center  as  rapidly  as  it  does  through 
the  regular  can.     The  other  kind  has  the  advantage  because  it  is 


PEAS.  367 

sealed  up  within  the  regular  can  and  is  always  under  the  same  con- 
ditions as  the  goods  which  are  being  packed. 

The  mercury  column  in  the  self-registering  tliermometer  is 
made  with  a  constriction  near  the  mercury  l)ulb;  so  whenever  the 
column  rises  to  a  certain  mark  it  remains  stationary  until  the  can 
is  opened.  In  this  way  the  maximum  temperature  will  be  indi- 
cated. 

To  make  a  series  of  tests  to  find  out  the  length  of  time  re- 
quired for  certain  temperatures  to  reach  the  center  of  a  can,  you 
will  proceed  in  the  regular  manner  by  gradually  raising  the  temper- 


£^J^  h 


.€? 


k 


.  0  B^ 

V 


Plate  125.     Anaerobic  Bacillus  X. 


Showing  rods  and  spores.  Formation  of  spores  was  rapid  at  98  degrees  F. 
in  incubator.  This  bacillus  produced  great  quantities  of  gas.  Isolated  from 
swelled  can  of  very  young  peas.  Odor  from  culture  very  foul.  Pure  culture  ob- 
tained by  the  pyrogallate  method.  Photomicrograph  with  acetylene  light  by  the 
author.     Magnified   1,200  diameters. 

ature  to  230°  F\  for  first  experiment.  After  maintaining  this 
degree  of  heat  for  twenty  minutes  you  allow  the  pressure  to  de- 
crease, chill  the  can,  open  and  examine  the  thermometer,  and  3^ou 
will  find  that  it  indicates  only  225°  F.  At  240°  F.  for  twenty 
minutes,  230°  F.  is  registered  at  the  center.  At  250°  for  twenty 
minutes  only  235°  have  been  registered. 

After  a  number  of  tests  I  have  prepared  a  table  which  shows 
the  time  required  for  the  heat  to  register  at  the  center  of  the  cans, 
using  different  lengths  of  time  and  different  degrees  of  heat. 

I  made  a  number  of  experiments  to  determine  the  length  of 
time  required  for  a  given  temperature  to  register  at  the  center  of  a. 


368  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

can  of  peas.  I  found  that  the  time  required  was  much  less  than 
that  for  corn,  owing,  no  doubt,  to  the  more  fluid  nature  of  the  con- 
tents. The  juice  of  the  peas  makes  a  very  good  carrier  of  heat 
from  the  tin  to  the  center  of  the  cans.  There  is  no  doubt  that  the 
center  of  hard  peas  is  less  penetrable,  consequentl}^  such  peas  will 
not  have  the  recorded  degree  of  heat  inside,  even  though  the  liquor 
does  register  a  certain  temperature.  There  would  be  only  a  small 
difference  with  small  size  peas,  but  the  older  varieties  would  prob- 
ably need  a  few  minutes  extra  time.  To  show  the  result  of  ex- 
periments with  self-registering  thermometers  I  will  give  the  re- 
sults as  recorded  in  my  notebook.  The  left  hand  column  will  show 
the  number  of  minutes  given,  while  the  different  degrees,  as  indi- 
cated by  the  retort  thermometer,  are  at  the  heads  of  the  columns : 

TABLE  SHOWS   HKAT   PENE:TRABIIJTY   OF   CANS   OF   PEAS. 

Minutes  230  235  240  245  250 


20 

225 

227 

230^ 

232.5 

235 

25 

226 

229 

232.5 

236 

240 

30 

227.5 

231 

235 

239-5 

244 

35 

229 

233 

237-5 

242 

248 

40 

2^ 

235 

240 

245 

250 

A  careful  study  of  this  table  brings  out  some  important  facts : 
230°  F.  for  forty  minutes  is  the  same  as  240°  F.  for  twenty  min- 
utes; 235°  F.  for  forty  minutes  is  the  same  as  240°F.  for  thirty 
minutes  and  250°  for  twenty  minutes.  It  requires  about  forty 
minutes  for  a  given  retort  temperature  to  be  recorded  at  the  center. 
Peas  processed  at  250°  for  thirty  minutes  reach  244°  F.,  Avhich 
makes  an  average  of  237"^  F.  for  at  least  fifteen  minutes. 

I  made  a  number  of  experiments,  using  various  temperatures, 
for  sterilizing  peas.  I  boiled. twelve  cans  in  open  bath  for  two 
hours,  then  put  them  in  the  incubator  to  favor  the  development  of 
hacteria,  should  any  be  left  alive  inside  the  cans.  Five  spoiled 
within  one  day,  three  spoiled  by  the  end  of  the  second  day,  and  two 
more  swelled  the  following  day.  Two  cans  seemed  to  be  all  right. 
They  did  not  swell,  although  kept  in  the  incubator  at  blood  tem- 
perature for  three  weeks.  On  opening  these  cans,  however,  they 
were  exceedingly  sour.  The  color  of  the  peas  was  much  bleached, 
but  otherwise  they  looked  fairly  well,  except  that  the  acid  was 
strong  and  surprised  me  very  much  when  I  tasted  them. 

I  melted  a  flask  of  agar  in  the  autoclay  at  240  degrees  F.,  then 
filled  six  Petri  dishes.  When  cooled  to  about  120  degrees  F.  I 
inoculated  two  with  several  loops  full  of  the  liquor  from  these  cans, 
then  made  transfers  from  the  first  two  into  two  more,  and  from 
these  made  transfers  into  two  more.     I  placed  the  dishes  in  the  in- 


PEAS.  369 

cubator  and  at  the  end  of  twenty- four  hours,  the  two  first  dishes 
were  completely  covered  with  a  thin  growth  extending  even  up  to 
the  walls. 

The  next  two  dishes  had  a  few  colonies,  but  the  greater  por- 
tion of  the  surfaces  were  covered  with  a  spreading  growth.  The 
two  last  dishes  contained  a  few  scattered  colonies  which  formed  in 
wedge  shape  or  whetstone  shape  below  the  surface,  and  grew  up- 
ward, forming  thin,  round  colonies  on  the  surface.  Some  of  these 
colonies  had  a  brown,  opaque,  granular  appearance  by  transmitted 
light,  but  on  reaching  the  surface  had  a  bluish  cast  with  a  shining 


V 


/ 


Plate  126 

Photomicrograph  of  Bacillus  X  found  in  can  of  sour  peas.  Forms  no  gas  and 
reduces  sugar  to  acids.  Bacilli  having  numerous  flagella,  which  are  stained  by- 
author's  special  method.    Magnified  1,500  diameters. 

transparent  luster.  The  surface  growth  extended  gradually  to 
about  the  size  of  a  silver  three-cent  piece,  the  lustrous  appearance 
giving  way  to  a  dull  scum-like  layer  quite  viscous  and  forming 
folds  or  wrinkles,  becoming  much  elevated. 

When  transplanted  to  gelatin  the  colonies  began  to  sink  into 
the  gelatin,  in  thirty-six  hours  leaving  saucer-like  depressions,  and 
a  floating  film  formed  on  the  surface  of  the  liquefied  gelatin.  The 
growth  in  bouillon  was  rapid,  producing  very  little  cloudines,  a 
pellicle  forming  on  the  top  which  grew  fast  to  the  wall  of  the  test 
tube. 

Colonies  on  agar,  when  viewed  by  carefully  lowering  a  J^  dry 
objective  into  focus,  present  a  wonderful  appearance.  The  bacilli 
are  seen  in  active  motion,  travelling  in  parallel  lines,  in  curves,  ex- 


370  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

hibiting  their  motility  in  twisted,  writhing  masses.  By  making  a 
suspension  in  distilled  water  and  carefully  staining,  I  was  able  to 
demonstrate  the  flagella  or  organs  of  locomotion. 

The  cultures  all  had  the  odor  of  sulphuretted  hydrogen,  and  in 
a  few  days  the  sulphur  would  be  strong  enough  to  bleach  out  the 
blue  color  made  with  the  marking  pencil  on  the  glass  Petri  dishes 
and  test  tubes.  I  inoculated  several  cans  of  peas  which  had  been 
sterilized,  with  some  of  these  organisms  and  in  two  or  three  days 
the  cans  had  the  same  appearance  and  taste  as  the  original  two  cans. 
I  tested  other  cans  by  inoculating  them  with  spores  from  this  or- 
ganism and  processing  at  240  degrees  F.  for  twenty-five  minutes. 
Of  the  twelve  cans  so  treated  onlv  two  were  sterilized.     Ten  of 


^*X  m^^  ^^, 


Plate  127 

Photomicrograph  of  Bacillus  X  showing  rods  and  spores.  Spores  are  free  and 
located  in  the  cells.  Spore  Membrane  is  quite  thick,  giving  them  great  heat-^ 
resisting  power.     Magnified   1,500    diameters. 

these  cans  had  a  natural  appearance,  showed  no  signs  of  swelling, 
but  turned  sour  in  five  days  in  the  incubator.  The  spores  of  this" 
organism  are  quite  large,  are  situated  near  the  middle  or  perhaps  a 
little  nearer  the  end  of  the  cell.  The  cell  seems  to  split  open  at  the 
side,  thus  setting  the  spore  free. 

One  dozen  cans  sterilized  for  twenty-five  minutes  at  250° 
F.  kept  all  right,  but  it  was  no  doubt  very  close  to  the  danger  line. 

I  tried  one  dozen  cans  heated  to  220°  F.  for  forty  minutes, 
but  all  spoiled;  some  swelled  and  burst  the  cans,  others  simply 
soured  and  the  liquor  became  much  clouded.  An  experiment  with 
six  cans  at  230°    for  forty  minutes  gave  pretty  good  results,  only 


PEA3.  371 

one  of  these  spoiled,  so  I  began  an  investigation  of  the  causes  of 
the  spoilage.  I  made  a  series  of  inoculations  in  Petri  dishes  as 
previously  described,  and  in  twenty-four  hours  had  a  very  fine 
growth  of  a  germ  answering  every  published  characteristic  of  ba- 
cillus mesentericus  ruber,  commonly  found  on  potatoes. 

This  is  a  somewhat  slender  bacillus  discovered  by  Globig,  who 
isolated  it  from  boiled  potato.  It  is  a  chromogenic  bacillus  form- 
ing a  pinkish  yellow  pigment.  It  is  an  aerobic  organism,  but  is  able 
to  grow  fairly  well  where  oxygen  is  almost  excluded.     I  remem- 


V 


* 


Plate  ]28 

Photomicrograph  of  Globig's  Bacillus  Mesentericus  Ruber,  a  chromogenic  ac- 
tively motile.  Bacillus  having  numerous  flagella,  as  here  shown.  This  Bacillus 
was  isolated  from  a  can  of  spoiled  peas  and  stained  by  author's  special  method. 
Culture  from  Agar   eight  hours'   growth.  Magnified  1,000  diameters. 

bered  well  that  the  can  I  had  opened  was  not  full  by  nearly  one  inch, 
so  that  enough  oxygen  was  present  to  give  sufficient  of  that  element 
for  the  growth  of  the  bacilli.  The  colonies  on  agar  were  a  yellow 
color,  and  those  which  lay  just  under  the  surface  came  rapidly  to 
the  top  and  began  spreading.  Under  a  magnification  of  'fifty  dia- 
meters, fine  points  w^ere  visible,  extending  outward  from  the  veil- 
like growth.  The  growth  on  gelatin  is  similar,  except  that  lique- 
faction begins  as  soon  as  the  colonies  begin  to  spread.  On  the  sur- 
face of  the  liquefied  gelatin  a  pink-like  film  forms.  In  the  test  tube 
stab  culture  this  film  spreads  to  the  walls  of  the  tube.  The  streak 
on  agar  is  viscid  witli  a  transparent  growth  extending  always  in 


372  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

advance  of  the  filmed  and  wrinkled  layer,  and  from  this  thin  growth 
we  are  enabled  to  get  the  most  actively  motile  rods.  The  flagella 
of  these  rods  are  always  very  numerous,  and  enable  them  to  travel 
forward,  rapidly  spreading  over  the  whole  surface.  The  spores 
of  this  vSpecies  are  probably  more  resistant  than  any  of  the  very 
common  varieties  of  bacilli,  excepting  those  of  bacillus  subtilis,  and 
some  varieties  common  to  the  soil.  They  are  larger  in  diameter 
than  the  cell  itself  and  are  oval.  The  spore  wall  is  quite  thick, 
which  accounts  for  its  great  resistance  to  heat. 


/ 


f 


S 


N  ft 


Plate  129 

Photomicrograph  of  rods  and  spores  of  Globig's  Bacillus  Mesentericus  Ruber. 
Spores  are  larger  than  the  rods  in  breadth.  Spores  are  able  to  withstand  boiling 
for  six  hours.  This  is  a  chromogenic  actively  motile,  aerobic  organism  first  found 
on  potatoes.  It  is  widespread,  being  found  on  peas,  corn,  beans,  etc.  Magnified 
1,000  diameters. 

When  these  spores  are  inoculated  into  cans  of  peas  they  soon 
spoil  and  it  is  remarkable  that  only  one  of  the  six  cans  processed  at 
240°  F.  contained  any  of  this  species.  I  believe  that  if  the  cans  are 
well  filled  with  liquor  the  small  amount  of  oxygen  present  would 
likely  interfere  with  the  growth  of  this  bacillus.  Cans  filled  nearly 
full  and  exhausted  contain  little  or  no  oxygen,  and  all  bacteria 
would  sbon  be  forced  to  grow  in  an  anaerobic  condition. 

A  certain  packer  once  sent  me  a  few  cans  of  peas  which  he 
had  processed  at  240°  for  twenty-five  minutes.  Almost  half  were 
sour,  having  living  bacteria  present  in  them.  The  liquor  was  quite 
cloudy  and  when  viewed  under  the  microscope,  in  a  hanging  drop, 
motile  organisms  were  seen  moving  quite  freely,  sometimes  singly, 
but  generally  two  together.     They  w^ere  slender  and  were  endowed 


PEAS.  373 


^  J''-  n 


\ 


Plate  130 

Photomicrograph  of  Bacillus  W,  an  actively  motile  aerobic  and  facultative 
anaerobic  Bacillus  found  growing  side  by  side  with  an  anaerobic  Bacillus  in  can 
of  spoiled  peas.  The  numerous  flagella  are  demonstrated  by  author's  special 
method.    Agar  culture  eight  hours'   growth.     Magnified  1,200  diameters. 


Plate  131 

Photomicrograph  showing  rods  and  spores  of  Bacillus  W.  Found  growing  with 
Bacillus  K  in  peas  which  had  been  processed  at  240  degrees  F.  for  twenty-five 
minutes.  From  Agar  culture  four  days  old.  Stained  with  fuchsine.  Magnified 
1,000  diameters. 


374  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

with  numerous  flagella.  I  isolated  these  by  plate  culture  and 
found  that  two  species  were  present,  one  belonged  to  the  group  of 
anaerobes  and  refused  to  grow  on  agar,  except  in  an  atmosphere  of 
hydrogen  or  by  the  pyrogallate  method.  I  was  able  to  get  a  good 
growth  of  both  by  a  stab  culture  in  agar  of  one,  and  a  surface 
growth  of  the  other  variety.  These  two  organisms  had  been  ac- 
customed to  grow  in  the  same  goods,  one  being  an  aerobe,  utilized 
all  the  oxygen  obtainable  and  produced  a  condition  of  anaerobsis 
which  was  favorable  for  the  growth  of  the  anaerobic  species.  The 
other  bacillus,  although  an  aerobic,  was  also  a  facultative  anaerobe, 
consequently  flourished  well  in  either  condition.  This  phenomenon 
is  often  seen  in  bacteriological  examinations,  in  so  much  that  we 
have  difficulty  at  times  in  separating  certain  species. 


Plate  132 

Photomicrograph  showing  Bacillus  K.  An  actively  motile  anaerobic  Bacillus 
found  growing  together  with  Bacillus  W  in  can  of  spoiled  peas.  This  was  isolated 
by  the  pyrogallate  method.     Very   numerous   flagella.     Magnified   1,500  diameters. 

Both  of  these  species  began  to  form  spores  in  three  days,  and 
I  inoculated  several  cans  of  peas  with  them  and  gave  them  240°  F. 
for  twenty-five  minutes,  and  then  put  them  in  the  incubator  at  98° 
F.  About  one  week  later  I  opened  these  cans  and  they  were  all 
right.  This  seemed  strange,  because  the  packer  who  had  experi- 
enced the  difficulty  had  given  them  this  very  process,  so  for  a  time 
I  was  puzzled  to  know  why  my  experiment  had  failed  to  show 
signs  of  spoilage.  I  streaked  agar  plates  with  the  juice  of  my 
cans,  but  did  not  obtain  any  growth  of  bacteria.  The  only  expla- 
nation I  am  able  to  make  is  that  his  peas  were  larger  and  harder 


PEAS. 


375 


than  tliose  in  the  cans  which  I  had  inoculated.     I  had  noticed  this 
when  I  opened  the  original  cans. 

There  is,  of  course,  another  explanation;  his  thermometers  and 
gauges  might  have  been  incorrect,  but  the  first  explanation  is  prob- 
ably right,  because  a  process  of  240°  for  twenty-five  minutes  is  too 
short  for  peas,  excepting  perhaps  the  very  smallest  sizes.  Even 
the  small  sizes  may  not  be  perfectly  sterilized  at  this  temperature. 
From  our  table  showing  the  penetrability  of  heat  by  the  test  of 
inside  thermometers,  we  find  that  only  230°  F.  is  registered  at  the 
center  of  the  cans  in  twenty-five  minutes  at  240  degrees,  and  this 


Plate  133 

Photomicrograph  of  Bacillus  K  showing  rods  and  very  small  spores.  Bacil- 
lus K  is  an  anaerobic  organism  found  growing  with  the  aerobic  Bacillus  W.  in 
a  can  of  peas  which  had  been  processed  at  240  degrees  P.  for  twenty-five  minutes. 
Slide  prepared  from  a  four  days'  growth  on  Agar  at  98  degrees  F.  in  incubator. 
Stained  with  fuchsine.     Magnified  2,000  diameters. 


is  hardly  sufficient  to  destroy  the  spores  in  all  cases. 

We  must  not  lose  sight  of  another  very  important  factor  in 
dealing  with  spores.  Old  spores,  those  which  have  become  dried 
or  have  been  in  a  resting  state  for  a  long  time,  will  be  more  difficult 
to  destroy  than  the  spores  which  have  formed  in  laboratory  cul- 
tures, which  may  be  only  several  days  old. 

Laboratory  cultures  of  bacteria,  as  a  rule,  are  more  readily  de- 
stroyed by  heat  than  the  same  bacteria  which  find  a  suitable  sub- 
stratum in  peas  in  the  field.     The  spores  which  get  into  canned 


376 


CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


peas  may  be  old;  they  may  have  been  in  a  dormant  state  for  a 
year  or  more,  and  consequently  are  dried,  and  the  spore  membrane 
may  have  shrunken  and  become  more  impenetrable.  Our  labora- 
tory cultures  of  the  spore-bearing  species,  usually  form  spores  with- 
in a  few  days,  and  these,  when  transplanted  into  sterile  cans  of  peas 
for  experimental  sterilization,  are  more  susceptible  to  heat  than  the 
kind  we  have  described.  Our  table  of  temperatures  employed  for 
sterilizing  peas  is  best  prepared  from  the  results  obtained  in  actual 
canning.  A  variety  of  spoilage  cases  are  recorded  in  our  note- 
book, and  we  will  put  the  results  of  the  various  processes  in  table 
form,  and  then  draw  some  practical  conclusion,  keeping  in  mind 
always,  the  various  sizes  of  peas,  also  the  location  of  the  canning 
establishment : 


Location       Size  of  Peas 


Temper- 
ature 


Minutes 


Living 
Bacteria 


Results 


Canada Marrowfats... 

Canada Early  June.. 

Canada Extra  Early 

Canada Petit  Pois 

Canada' Petit  Pois 


Degrees 

....240 

....240..., 

....240 

.  .240 

..  238... 


1.  Mich.... Marrowfats 240... 

Mich Extra  Early 240... 

Mich Extra  Small 240.. 

2.  Mich No.  4 240.. 

Mich No.  3 5^40.. 

Wisconsin No.  4 235  .. 

Wisconsin No.  3 235 35.. 

Wisconsin No.  2 235 30. 

Wisconsin No.  1 235 30.. 

New  York Marrowfats 240 35  . 

New  York Extra  Early 240 30. 

New  York Small 240 25. 

Ohio Marrowfats 240 40., 

Ohio  Early  June 240 35.. 

Ohio   Extra  Early.,.'. 240 30. 

Ohio    Small  240 2=i. 

Indiana  No.  4 210 38., 

"  branch 

factory..No.  4 235 38. 

Indiana No.  3 235 38 

Indiana No.  2 235 35. 


Indiana Petit  Pois. 


.235. 


2.  Indiana Early  June 210. 

Illinois  No.  4 240. 

■°- {k'As;} ^« 

Penna Telephone  250 

Penna  Telephone  250. 

Penna  Early  June  250. 

Penna Very  Small 250  . 


.present About  20^  sour,  few  swells  " 

.present About  5^  sour,  cloudy  liquor 

.present About  b%  sour, cloudy  liquor 

.present About  2^  sour,  cloudy  liquor 

.none  Kept  well 

.none  Kept,  cloudy  liquor]    due  to 

none  Kept  |>  sweating 

.none  .: Kept  j  ofvlnes 

none  Sour  before  canning 

.none  Sour  before  canning 

present lOn^  sour,  some  swells 

present 10^  sour,  some  swells 

present 10*  sour,  some  swells 

present A  few  sour 

none    Kept 

.present A  few  sour  and  swelled 

.present A  few  sourand  swelled 

.none  All  kept 

present A  few  sour  and  swells 

.present A  few  sour 

.none  All  kept 

.present A  few  sour,  some  swells 

.none  All  kept 

..none  All  kept 

.present Sourand  cloudv  liquor 

•— Cloudy  liquor  {S'ci"p^ea1 

nrp^pnf  I  Large  number  swelled 

P^^^^"^ \  Exhaust  line  clogged 

.present A  few  sour 

present A  few  sour,  cloudy  liquor 

.present Soured  after  2  weeks 

.none  Kept  well 

none  Kept  well 

.  none  Kept  well 


After  studying  these  different  cases  we  see  that  the  chances 
of  spoilage  at  240°  F.  for  any  time  less  than  forty  minutes  is  great, 
and  we  are  impressed  with  the  conviction  that  240°  F.  is  not  a 
very  reliable  temperature.  Perhaps  in  Canada  and  the  northern 
states  240°  F.  for  forty  minutes  is  sufficient  for  all  large  and  medi- 
um ■  sizes  and  the  very  small  sizes  might  keep  well  at  the  same 
temperature  for  thirty-five  minutes,  unless  the  weather  should  be 
hot  and  rainy,  in  which  case  the  temperature  should  be  increased. 

In  the  central  states  we  should  recommend  250°    F.  for  thirty 


PEAS.  377 

minutes  for  large  sizes,  and  twenty-li^•e  minutes  for  the  small  sizes. 

This  cannot  be  laid  down  as  a  positive  rule,  however,  but  we 
may  outline  a  definite  method  of  ascertaining  positively  the  best 
temperature  under  all  conditions. 

If  the  peas  are  worked  up  promptly  and  not  allowed  to  go 
through  any  sweating  process,  the  skins  being  firm  and  strong,  we 
would  recommend  that  250°  for  thirty  minutes  be  tried  first,  and 
if  they  hold  up  all  right  and  do  not  crack  open  and  cloud  the  liquor, 
that  process  will  give  good  satisfaction.  The  alum  in  the  blanching 
bath  will  help  to  give  firmness  to  peas,  so  that  this  temperature  may 
be  used  with  safety.  If,  however,  the  peas  are  too  tender,  the  time 
should  be  cut  down  to  twenty-five  minutes  and  the  result  carefully 
noted.  It  is  a  good  plan  to  have  an  incubator  in  some  part  of  the 
factory,  "and  a  good  microscope  is  almost  indispensable.  After  a 
certain  process,  a  few  cans  out  of  each  batch  may  be  placed  in  the 
incubator,  and  kept  in  a  tem.perature  of  98°  F. — blood  temperature 
— and  if  the  sterilization  is  imperfect,  there  will  be  a  growth  of  bac- 
teria wuthin  twenty-four  to  thirty-six  hours.  Here  is  where  a  good 
microscope  wath  a  1-12  homogeneous  oil  immersion  objective,  is 
most  valuable.  The  cans  in  the  incubator  are  removed  one  at  a 
time,  the  juice  poured  out  into  a  clean  dish  and  drops  of  the  juice 
exam.ined  carefully.  A  simple  method  of  examination  is  made  by 
placing  a  drop  in  the  center  of  an  ordinary  microscope  slide,  then 
dropping  a  clean  coverglass  over  this,  so  as  to  have  the  juice  be- 
tween the  two  pieces  of  glass.  A  tiny  drop  of  cedar  oil  is  then 
placed  on  the  center  of  the  coverglass,  and  the  iris  diaphragm  is 
closed  so  that  the  hole  for  admission  of  light  is  about  as  large  as  a 
pin-head  in  diameter.  The  light  is  then  focused  with  the  concave 
mirror  and  the  Abbe  condenser;  the  1-12  oil  immersion  objective 
is  carefully  lowered,  by  means  of  the  coarse  adjustment,  until  it 
touches  the  oil,  and  then  it  is  brought  Into  focus  by  the  fine  adjust- 
ment, being  very  careful  not  to  let  it  crush  through  the  glass,  which 
might  destroy  the  delicate  lens.  In  this  connection  we  might  refer 
our  readers  back  to  the  description  of  a  hanging  drop  examination 
in  Chapter  III. 

If  the  microscope  is  equipped  with  a  mechanical  stage,  the 
fields  of  view  may  be  changed  with  precision,  and  the  presence  of 
any  motile  bacteria  may  be  noted  very  readily.  By  reference  to  the 
numerous  plates  of  various  species  of  bacteria  found  in  peas,  it 
may  be  possible  that  some  will  be  found  which  bear  close  resem- 
blance to  our  illustrations.  If  no  bacteria  can  be  seen  by  the 
methods  described,  it  is  a  simple  matter  to  stain  a  few  coverglasses 
evenly  spread  with  the  juice.  The  staining  methods  described  in 
Chapter  III  will  help  any  one  to  accomplish  this  feature  of  the  bac- 
teriological technique  with  ease  and  certainty.     It  is  not  always 


378  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

easy  for  beginners  to  find  living  bacteria,  because  they  are  almost 
colorless,  and  the  fluid  is  apt  to  form  currents  and  confuse  any  one 
not  familiar  with  this  kind  of  examinations.  A  little  practice  with 
stains  first,  and  living  bacteria  afterwards,  will  soon  help  the  be- 
ginner to  get  accurate  results.  After  acquiring  a  little  experience, 
the  juice  from  a  number  of  cans  may  be  examined  in  a  short  time, 
and  the  presence  or  absence  of  living  bacteria  may  be  ascertained 
with  accuracy.  By  following  up  the  practical  work  with  the  scientific 
it  becomes  an  easy  matter  to  keep  wxll  informed  on  the  safety  of 
of  every  day's  work.  After  a  time  the  various  results  following  each 
amount  of  sterilization,  ordinarily  given  peas,  will  furnish  to  the 
trained  eye — by  the  aid  of  the  microscope  and  the  appearance  of 
the  goods — all  the  necessary  evidences  of  imperfect  sterilization, 
whether  too  short  or  too  much  prolonged. 

We  can  thus  sum  up  the  points  brought  out  under  the  head  of 
peas : 

There  must  be  no  delays  after  the  vines  are  cut.  Good  judg- 
ment must  be  exercised  in  directing  the  cutting  to  avoid  overcrowd- 
ing the  viners.  If  the  vines  are  piled  up  in  cribs  or  stacks,  lactic 
fermentation  get  well  started  even  in  a  short  time.  During  rainy 
weather  the  work  must  be  close  up;  the  wet  vines  will  sour  very 
quickly.  When  lactic  acid  forms  in  peas  it  is  never  neutralized  after- 
ward. 

''Sweating"  softens  the  fiber  or  cellulose,  and  such  peas  will 
cloud  the  liquor.  ''Sweating"  to  the  extent  of  forming  butyric, 
lactic  and  fatty  acids,  will  cause  "slimy"  peas. 

The  cleaning,  separating  and  hand  picking  must  follow  the 
viners  quickly,  to  avoid  souring. 

The  blanching  should  be  done  in  running  water  if  possible;  a 
figal  cold  water  alum  bath  might  be  well  recommended,  then  a  spray 
of  cold,  clear  water. 

The  filling  should  be  uniform.  Do  not  fill  cans  too  full,  about 
three-quarters  of  an  inch  from  the  top  of  cans  is  about  correct. 

For  making  brine  use  either  spring,  well  or  filtered  water. 

Never  use  saccharin  as  a  sweetener,  it  is  a  violation  of  pure 
food  laws  in  many  states,  and  deceives  the  consumer. 

Note. — The  peculiar  sweet  taste  of  saccharine  will  soon  pre- 
judice the  consumer  against  peas.  I  have  made  several  experi- 
ment lately  to  ascertain  this  truth.  Saccharin  is  not  a  food ;  it  may 
have  medicinal  value  in  some  cases,  but  when  added  to  peas  or  other 
foods  it  is  deemed  an  adulterant,  and  by  various  authorities  is 
branded  as  injurious. 

Use  granulated  sugar  if  a  sweetener  is  necessary.  Have  good 
machinery  and  sufiicient  to  avoid  overcrowding  at  any  time. 


PEAS.  379 

For  sterilizing  use  250°  F.,  in  preference  to  240°  F. ;  it  is 
more  reliable  and  saves  time.  Thirty  minutes  for  large  sizes  and 
twenty-five  minutes  for  small  sizes  may  be  stated  as  a  broad  rule — 
this,  of  course,  may  be  varied  if  conditions  make  it  necessar}^ 

Always  chill  the  cans  before  opening  the  retorts,  by  turning 
cold  water  into  them.  See  diagram  of  process  kettle,  Chapter  VI, 
Fig.  31. 

The  calcium  system  offers  some  advantages  in  sterilization.  The 
revolving  crates  will  permit  the  heat  to  penetrate  to  the  center  of 
the  cans  more-  rapidly  than  in  the  retort  system.  The  time  may 
therefore  be  shortened  a  little. 

IvABORATORY    WORK    ON    PEAS. 
SP0II.AGE   OF   PEAS. 

vSome  of  the  processes  as  given  out  from  various  sources  are 
not  altogether  reliable,  and  such  losses  as  have  been  reported  up 
to  this  time  are  caused  by  insufficient  sterilization.  Insufficient 
sterilization  is  shown  in  two  ways — the  losses  from  swells  and  sour- 
ing without  any  formation  of  gas.  In  the  case  of  swells  large 
quantities  of  gas  are  formed;  this  is  due  to  bacteria  belonging 
largely  to  the  putrefactory  organisms,  especially  to  the  anaero- 
bic species  universally  distributed  in  the  soil,  the  spores  of  which 
are  found  on  the  pods,  leaves  and  vines  of  peas,  carried  there  no 
doubt  in  particles  of  dust.  The  spores  of  anaerobic  bacteria  are 
not  as  resistant  to  the  influence  of  high  temperatures,  as  the  spores 
of  other  varieties  which  do  not  form  any  gas.  Some  of  the  aero- 
bic bacteria  do  not  form  gas  when  growing  in  cans  of  peas,  and 
nearly  all  of  the  conmion  spore  bearing  aerobes  are  able  also  to 
grow  anaerobically.  This  class  of  bacteria  causes  the  greatest  and 
most  complete  losses  in  peas,  corn,  beans,  asparagus,  etc.,  because 
the  decomposition  is  not  evidenced  by  any  swelling  of  the  cans,  and 
usually  is  not  discovered  until  after  quite  a  lapse  of  time.  Some- 
times the  souring  is  quite  slow,  and  does  not  show  until  two  or  three 
weeks  after  the  peas  are  packed;  sometimes  the  time  is  much 
longer. 

Any  sterilizing  process  which  is  followed  by  swells  is  very  far 
below  what  it  should  be  because,  as  we  have  said,  that  form  of 
spoilage  is  accomplished  by  a  class  of  bacteria  less  resistant  to  heat 
than  the  class  which  produces  acidity  without  the  formation  of  gas. 
In  Bulletin  249  of  the  New  York  Agricultural  Experiment  Station 
at  Geneva,  Messrs.  Harding  and  Nicholson  made  a  number  of  ex- 
periments to  determine  the  cause  of  the  malodorous  decomposition 
of  canned  peas,  and  also  the  amount  of  heat  necessary  to  destroy 
the  bacteria.  The  bacteria  responsible  for  swells  as  they  found 
them  are  anaerobes,  and  not  the  most  resistant  forms. 


380  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

We  have  often  isolated  these  from  botli  peas  and  corn.  They 
are  ahiiost  as  difficult  to  cultivate  (on  artificial  media),  as  the 
Bacillus  tetanus,  or  lockjaw  germ.  In  our  laboratory  work  we 
find  that  such  organisms  thrive  best  on  a  medium  prepared  with  the 
juice  of  the  very  goods  in  which  we  find  them  growing.  Fre- 
quently we  find  that  we  get  a  very  poor  growth  on  agar  prepared 
with  meat  juice  and  peptone.  After  obtaining  sub  cultures,  how- 
ever, they  do  pretty  well.  The  cultivation  of  anaerobic  bacteria 
to  obtain  a  superficial  growth  is  quite  difficult,  and  since  this  is  the 
only  kind  of  a  culture  that  is  fit  for  staining  the  young  rods  in  order 
to  demonstrate  the  flagella,  or  organs  of  locomotion,  great  care 
must  be  exercised  in  the  technique.     As  we  have  stated,  the  anae- 


r 


Plate  134 

Photomicrograph  of  a  Bacillus  found  in  can  of  swelled  peas.  This  organism 
answers  to  the  description  of  Bacillus  Butyricus  (by  Piazmowski).  This  plate  shows 
the  motile  vegetating  rods.  The  germs  were  cultivated  anaerobically  by  the  pyro- 
gallate  method.  Stained  by  our  special  method  and  photographed  through  1-12 
Spencer  objective.     Magnified   1,500   diameters. 

robic  bacteria  grow  only  where  oxygen  is  entirely  excluded,  that 
gas  in  the  free  state  being  poisonous  to  them,  it  must  either  be 
replaced  by  hydrogen  or  absorbed  by  chemicals.  We  are  very  suc- 
cessful in  growing  these  anaerobes  by  the  pyrogallate  method, 
which  is  done  by  sealing  loosely  stoppered  tubes  containing  the  in- 
oculated or  streaked  agar,  in  a  jar,  previously  adding  enough  al- 
kaline fluid  to  neutralize  a  given  quantity  of  pyrogallic  acid.  This 
mixture  is  poured  into  the  jar  and  the  culture  tubes  are  placed  in- 
side and  the.  jar  is  then  sealed  absolutely  tight  with  sealing  wax. 
We  obtain  the  best  results  by  first  growing  a  pure  culture  in 
the  clear  juice,  in  the  anaerobic  jar,  and  then  from  this  we  streak 


PEAS.  381 

slanted  agar  tubes,  using-  a  liberal  quantity  of  the  juice  to  cover  the 
surface  of.  the  slant.  After  two  days  we  generally  get  a  good  su- 
perficial or  surface  growth.  A  small  quantity  of  this  growth  mixed 
with  water  and  thinly  spread  over  the  surface  of  a  coverglass  is 
generally  all  right  for  staining.  The  staining  for  the  demonstra- 
tion of  flagella,  as  shown  in  Plate  134,  is  a  very  difficult  task,  re- 
quiring experience  and  judgment  to  obtain  good  results.  Many 
failures  may  be  expected  ere  a  first-class  preparation  fit  for  photo- 
micrographing  is  obtained. 

Spore  bearing  bacilli  of  this  class  form  spores  rapidly,  especi- 
ally in  the  incubator,  and  when  this  stage  is  reached  the  flagella 
cannot  be  easily  demonstrated.  Many  of  those  delicate  hair-like 
organs  of  locomotion  drop  off  and  are  dissolved  in  the  surrounding 
fluid,  leaving  the  rod  with  its  bright  spore  nearly  devoid  of  flagella. 
In  such  preparations  the  spores  are  seen  both  in  the  rods  and  also 
free,  as  shown  in  Plate  135.  The  spores  are  the  resistant  forms  of 
bacterial  life.  They  may  be  regarded  as  the  seed  forms.  The 
spores  are  formed  within  the  rods  and  the  first  indication  of  spore 
formation  is  the  appearance  of  granules  throughout  the  cell,  which 
soon  collect  in  a  certain  place,  at  first  as  an  irregular  mass,  gradu- 
ally assuming  a  round  or  ellipsoidal  form  and  becoming  brighter 
and  more  refractive,  having  a  wall  or  distinct  membrane.  This 
membrane  becomes  thicker  and  protects  the  life  within,  just  as 
the  membrane,  which  surrounds  a  dry  mustard  seed,  be  an  or  pea. 
It  prevents  heat  from  penetrating  to  the  inside;  even  boiling  tem- 
peratures are  resisted  for  several  hours.  Spores  form  in  the  rods 
only  when  conditions  become  unfavorable  for  multiplication.  Re- 
production or  multiplication  is  the  natural  characteristic  of  bacteria, 
but  this  soon  ceases  in  culture  media,  because  the  supply  of  nour- 
ishment is  limited,  and  there  is  no  provision  for  carrying  off  the 
products  excreted  by  the  bacteria.  In  cleavage  processes  the  com- 
pounds which  are  formed  are  often  poisonous  to  the  germs  and  act 
as  antiseptics.  It  is  due  to  this  fact  that  the  antitoxins  used  in  dis- 
eases are  so  valuable.  The  toxins  are  poisonous  to  the  germs 
themselves,  and  render  the  medium  upon  which  they  are  growing 
unfit  for  their  multiplication,  hence  spores  are  formed  which  have 
the  power  to  resist  the  poisons,  until  such  time  as  they  may  find 
lodgment  in  a  more  suitable  substratum.  This  power  to  resist  an 
unfavorable  environment  is  the  secret  of  the  difficulty  experienced 
in  sterilizing  canned  goods  without  injuring  the  quality.  As  a  rule 
the  line  of  safety  in  sterilization  is  so  close  to  the  line  of  danger 
from  scorching  that  it  is  sometimes  quite  difficult  to  produce  goods 
which  will  keep  well  and  still  retain  much  of  the  natural  flavor. 
Sterilization  will  always  change  the  flavor  to  some  extent,  but 
eoods  must  not  have  a  scorched  taste  or  odor.     It  cannot  be  laid 


382  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

down  as  a  positive  rule  that  peas  will  be  processed  properly  at  a 
temperature  of  240°  F.  for  25  to  30  minutes.  We  have  on  record 
a  number  of  spoilage  cases  where  this  temperature  failed.  While 
a  number  of  packers  will  testify  that  this  has  always  been  sufficient 
for  their  peas,  there  are  still  others  who  have  lost  considerable 
money  on  account  of  sour  peas.  The  only  possible  way  to  know 
just  what  temperature  is  sufficient  is  by  bacteriological  examina- 
tion. I  have  sterilized  peas  perfectly  at  250°  F.  for  15  minutes, 
but  I  know  that  it  would  be  ruinous  to  use  such  a  process  uni- 
versally. In  the  laboratory  we  have  sterilized  peas  and  corn,  too, 
in  20  minutes'  exposure  to  240°  F.,  but  it  happened  that  the  raw 
product  was  free  from  some  of  the  resistant  varieties.  It  is  pretty 
safe  to  start  out  with  a  process  of  250°  F.  for  about  25  minutes; 


Plate  135 

Photomicrograph  of  the  spore  forms  of  the  Bacilli  shown  in  Plate  134.  The 
spores  are  terminals  and  much  larger  in  breadth  than  the  rods.  These  spores  are 
resistant  to  high  temperatures  and  vegetate  only  in  an  anaerobic  condition.  Photo- 
graphed  through  the   microscope   under   a   magnification   of   1,500   diameters. 


some  of  the  cans  may  then  be  placed  in  a  warm  place  for  two  or 
three  days,  and  the  juice  may  then  be  examined  under  a  one-twelfth 
homogeneous  oil  immersion  lens.  Since  nearly  all  of  the  bacteria 
identified  with  spoilage  are  motile,  the  rods  may  be  seen  swimming 
around  in  the  juice.  We  would  recommend  a  temperature  of  250° 
F.  for  25  to  30  minutes.  One  or  two  cans  sent  to  the  laboratory  by 
express  will  reach  us  within  24  hours  in  most  cases,  and  we  are  well 
equipped  to  examine  any  goods  and  report  by  wire  if  necessary  to 
increase  the  time. 


PEAS.  383 

The  following  letter  is  one  which  must  be  interesting  to  every 
packer  because  it  is  a  description  of  the  difficulties  and  losses  which 
have  befallen  many,  and  seemed  so  mysterious,  too : 

Prof.  E.  W.  Duckwall,  care  of  National  Canners'  Laboratory,  As- 
pinwall.  Pa. 

Dear  Sir: — We  are  sending  you  by  express  today,  charges 
prepaid,  a  box  containing  six  cans  of  peas.  These  were  absolutely 
fresh  stock,  shelled,  cleaned,  filled  and  processed  without  any  delay, 
and  cooked  under  ten-pound  pressure  twenty-five  minutes  after  the 
glass  showed  240^  ;  then  cooled  and  stacked  in  cases.  The  swelling 
shows  about  a  week  after  being  cooked,  and  seems  to  be  very  gen- 
eral, from  present  appearance,  perhaps  one-fourth  of  the  pack. 
We  have,  on  noticing  this  condition,  increased  our  cook  to  fifteen- 
pound  pressure,  or  250°,  and  find  that  we  have  the  difficulty 
stopped,  but  we  are  at  a  loss  to  understand  the  conditions  that  ex- 
isted in  the  first  two  wrecks'  pack.  We  have  cooked  our  peas  for 
the  past  three  years  at  the  ten-pound  pressure,  and  from  twenty  to 
thirty  minutes,  and  have  had  no  trouble  of  any  moment.  This  was, 
too,  wlien  our  factory  was  crowded,  and  the  peas  did  not  go 
through  the  process  as  promptly  as  they  have  this  season.  Also, 
w^hen  they  had  to  be  delayed  in  threshing  other  seasons  on  account 
of  excessive  deliveries ;  in  fact  all  the  conditions  in  our  factory  this 
year  are  25  per  cent  better  than  they  have  been. 

Another  point  is,  that  we  have  insisted  on  our  goods  being  de- 
livered at  an  early  stage  of  growth,  and  the  result  being  that  w^e 
have  packed  very  much  larger  of  high-grade  goods  and  this  loss 
coming  at  this  time  is  exceedingly  trying,  and  we  would  appreciate 
very  much  your  assistance. 

You  may  perhaps  remember  the  writer  meeting  you  at  Co- 
lumbus last  February  and  talking  over  this  very  point  of  processing 
peas,  and  you  expressed  your  views  at  that  time  that  we  would 
probably  have  to  increase  our  temperature. 

Thanking  you  for  your  interest  in  the  matter,  we  beg  to  re- 
main. 

Very  truly  yours. 


The  six  cans  arrived,  three  of  them  bursted  and  contents  gone. 
The  odor  was  very  bad,  showing  that  putrefactive  bacteria  had  ac- 
complished the  spoilage.  The  three  remaining  cans  were  badly 
swelled,  and  when  punctured  the  force  of  the  gas  caused  the  juice 
to  spurt  out  in  a  stream.  We  quickly  streaked  a  number  of  petri 
dishes  and  agar  slants,  also  inoculated  some  tubes  of  liquid  culture 
media.  Part  of  tll^se  were  placed  in  anaerobic  jars,  so  that  the 
anaerobic  bacteria  might  form  colonies  along  with  the  facultative 


384 


CANNING  AND  PRESERVING  OP  FOOD  PRODUCTS. 


aerobes.  After  two  days  quite  a  number  of  colonies  made  their  ap- 
pearance, some  of  each  species.  The  anaerobic  bacteria  were  rods 
which  formed  terminal  spores  as  shown  in  Plates  134  and  135. 
The  facultative  anaerobic  bacteria  formed  small  colonies  in  the  jar, 
but  in  the  petri  dishes  the  colonies  developed  better,  where  free 
oxygen  was  accessible.  The  colonies  were  found  with  a  lustrous 
appearance,  bluish  white,  with  opaque  centers.  Under  a  magnifi- 
cation of  60  they  appeared  granular  with  rough  margins.  The 
agar  streak  was  a  dirty  white  growth  in  folds.  Streaked  from  a 
fresh  bouillon  culture  the  growth  was  moist  and  spreading,  and 
from  this  we  were  able  to  get  a  preparation  for  staining  flagella,  or 
organs  of  locomotion,  as  shown  in  Plate  136. 


Plate  136 

Photomicrograph  of  the  pea  bacillus,  which  resembles  Bacillus  Subtilis.  This 
shows  the  young  vegetating  rods  and  the  organs  of  locomotion  called  flagella. 
This  organism  produces  spores  of  great  vitality.  It  is  difficult  to  destroy,  much 
more  so  than  the  bacillus  shown  in  Plates  134  and  135.  Stained  by  author's  method 
and  photographed  through  the  microscope.     Magnified  1,500  diameters. 


The  spore  formation  took  place  in  the  center  of  the  rod,  as 
shown  in  Plate  137.  This  organism  produced  spores  rapidly.  It 
was  not  possible  to  get  motile  growths  by  transplanting  from  one 
surface  growth  to  another  in  agar,  spores  formed  almost  as  rapidly 
as  the  new  growth  appeared.  The  only  way  we  were  able  to  get 
the  true  growth,  one  that  would  show  flagella  in  staining,  was  from 
a  fresh  bouillon  culture  streaked  on  i^  per  cent  agar,  and  then 
from  a  six  or  eight  hours'  growth.  The  anaerobes  would  not  grow 
well  in  the  bouillon  at  first,  but  afterwards  \te  were  able  to  get 
fairly  good  results.     The  bacilli  have  round  ends  3  to  10  /^  long 


PEAS.  385 

and  I  to  1.5  />t  thick.  (A  /x  is  equal  to  one-twenty-five  thousandth 
of  an  inch.)  The  rods  grow  in  chains  and  form  spores  at  the  ends 
or  near  the  center,  in  the  latter  case  giving  the  cell  a  very  plump 
appearance  like  a  spindle.  This  is  called  a  Clostridium  form.  The 
cells  are  quite  motile  when  young,  and  endowed  with  numerous 
flagella,  as  shown  in  Plate  134.  The  spores  form  rapidly  and  are 
thicker  than  the  rod  itself.  They  measure  from  T.8  to  2.6  /x  in 
thickness.  When  vegetating,  the  spore  is  ruptured  at  the  end,  and 
the  young  rod  pushes  out.  One  spore  produces  only  a  single  rod. 
The  rods  lengthen  and  divide  and  this  is  the  manner  of  multiplica- 
tion, true  of  all  bacteria  excepting  the  micrococci  or  round  forms. 
This  organism  forms  butyric  acid,  carbon  dioxid  and  the  hydrogen 
combines  with  sulphur  and  hydrogen  sulphid  is  formed.  This 
is  the  organism  which  softens  the  fiber  and  causes  decomposition 


'<M^-  ■     -^  '■^ 


4 


c 


^,  f 


Plate  137 

Pea  Bacillus  No.  2.  Photomicrograph  showing  rods  and  spores.  Culture  from 
juice  of  peas,  stained  with  carbol  fuchsine.  Slide  preparation  by  the  author. 
Magnified'  X  1,000. 


of  cellulose,  in  which  case  march  gas  or  methane  is  sometimes 
formed.  When  starch  is  added  to  a  cuhure  medium  and  a  growth 
of  these  bacilli  is  obtained,  they  may  be  stained  with  iodine  and  a 
beautiful  blue  stain  is  obtained.  The  cells  of  the  bacteria  will 
take  in  the  starch  and  of  course  the  blue  reaction  of  iodine  follows 
the  staining.  This  is  a  beautiful  experiment  in  staining  and  helps 
us  to  identify  the  germ  as  one  answering  the  description  of  Bacillus 
Butyricus  ( Prazmowski )  or  Bacillus  Amylobacter,  a  very  common 
organism  found  in  putrefying  vegetable  infusions  in  cheese,  milk, 
etc. 


386  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

The  very  fact  that  the  anaerobic  bacteria  were  present  indicates 
that  the  process  used  (240°  F.  for  25  minutes)  was  much  too  low, 
because  a  temperature  sufficient  to  destroy  the  spores  of  this  species 
was  not  sufficient  to  destroy  the  spores  of  the  other  variety,  as  we 
found  by  actual  test.  We  recommended  that  250°  F.  be  used  for 
25  or  30  minutes.  The  packer  states  in  his  letter  that  the  process 
given  these  peas  was  the  same  as  that  successfully  used  for  three 
years  previously,  and  that  the  peas  went  through  very  promptly 
without  any  delays  as  formerly  in  the  threshing;  that  conditions 
were  25  per  cent  better  than  they  were  in  past  seasons,  and  that 
the  peas  were  younger  and  better  than  usual  in  quality  for  high 
grade  goods.  This  would  seem  very  mysterious  to  any  one  not 
acquainted  with  the  biological  characteristics  of  bacteria,  but  the 
reason  we  shall  endeavor  to  explain. 

When  peas  are  allowed  to  stand,  especially  in  piles,  they  be- 
come heated,  and  then  follows  what  is  called  a  ''sweating  process." 
This  sweating  is  caused  by  bacteria  starting  with  the  lactic  acid 
bacteria,  which  attack  the  carbohydrates,  converting  them  into  lac- 
tic acid,  the  fibre  softens  and  the  heat  generated  causes  the  spores 
of  various  species  of  bacteria  to  swell  and  vegetate.  The  aerobes 
and  facultative  anaerobes  begin  to  vegetate  first  on  the  surface,  thus 
utilizing  all  the  available  atmospheric  oxygen,  then  the  spores  of 
the  anaerobes  soften  and  begin  to  vegetate,  so  that  by  the  time 
the  peas  reach  the  steriHzing  process  all  spores  are  softened,  and 
many  have  no  doubt  vegetated.  In  the  sterilizing  process  they 
are  destroyed  by  a  temperature  considerably  less  than  would  have 
been  required  if  the  peas  had  been  worked  up  quickly  before  the 
spores  had  started  to  vegetate.  On  first  thought  it  would  seem 
better  to  let  peas  stand  a  short  time  to  allow  the  spores  to  soften  in 
order  to  be  sure  of  the  sterilization.  This,  in  fact,  is  the  condition 
in  a  great  many  canneries,  as  the  letter  indicates  there  were  numer- 
ous delays  in  the  threshing  during  previous  seasons,  and  those 
very  same  delays  are  the  rule  rather  than  the  exception.  It  cer- 
tainly follows  that  a  process  used  successfully  with  peas  handled 
in  the  manner  just  described  will  suddenly  fail  if  tised  on  strictly 
fresh  peas.  It  must  not  be  understood  from  this  that  serious  de- 
lays are  common  in  nearly  all  factories;  we  do  not  mean  this,  but 
there  are  only  a  very  few  who  work  up  the  peas  without  some  de- 
lays. Where  the  delays  are  serious,  there  is  formed  sufficient  lactic 
acid  to  cause  sour  peas. 

No  amount  of  sterilization  will  destroy  the  lactic  acid  when 
once  formed,  and  the  goods  will  be  distinctly  sour  after  the  cans 
are  opened,  and  in  this  case  the  liquor  is  frequently  much  clouded. 
The  formation  of  lactic  acid  begins  very  soon  if  the  vines  or  shelled 
peas  are  allowed  to  stand  for  any  length  of  time,  and  this  acid  de- 


PEAS. 


387 


stroys  the  fine  flavor  of  the  peas  according  to  the  amount  present. 
The  modern  method  of  cutting  the  vines  and  threshing  out  the 
peas  has  some  disadvantages  over  the  old  method  of  hand  picking, 
because  the  juice  is  necessarily  more  exposed.  But  this  is  more 
than  compensated  by  the  many  advantages  in  other  ways,  so  that 
a  better  and  more  uniform  quality  may  be  secured  if  the  arrange- 
ments are  complete  for  taking  care  of  the  peas  as  rapidly  as  they 
are  hauled  in. 

We  may  draw  this  conclusion  from  our  study  of  the  bacteria 
associated  with  peas.  Absolutely  fresh  stock  has  more  resistant 
spores  than  raw  material  which  has  been  exposed  for  a  limited  time, 
and  will  therefore  require  a  little  higher  temperature  to  insure 
perfect  sterilization. 


LID-EDGEVIEW 

Fig.  34.     Process  KeUle 


The  quality  of  freshly  canned  peas  will  be  very  much  superior 
even  if  the  process  is  higher  ,because  no  lactic  acid  is  present ;  250° 
F.  for  25  to  30  minutes  will  be  found  quite  sufficient,  but  if  there 
is  any  evidence  of  scorching,  this  must  be  cut  down,  because  it  is 
not  necessary  to  scorch  any  goods  to  insure  sterilization.  A  per- 
fect arrangement  for  chilling  the  cans  is  essential  and  the  employ- 
ment of  alum  after  the  blanching  is  to  be  recommended  for  its  as- 
tringent action  on  the  skins  of  the  peas,  which  prevents  their  burst- 
ing during  sterilization.     Cloudy  or  muddy  liquor    will    thus    be 


388  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

avoided,  but  all  traces  of  the  alum  should  be  washed  off  with  cold 
w^ater  before  the  peas  are  filled  into  the  cans. 


SPOII.AGE:    OF    CANNED    PE:AS. 

It  is  a  matter  of  wonder  to  us  that  some  of  the  processes  re- 
ported were  sufficient  in  any  degree.  In  reply  to  numerous  letters 
of  inquiry  in  the  past,  w^e  have  called  attention  to  the  fact  that 
perfect  sterilization  of  peas  could  not  be  accomplished  under  250° 
F.  for  25  or  30  minutes,  and  yet  we  have  reports  from  various 
sources  where  the  packers  have  used  only  240°  F.  for  as  short  a 
time  as  16  to  18  minutes.  Let  us  say  that  this  temperature  is  en- 
tirely too  low.  While  it  might  possibly  be  sufficient  for  some  cans 
we  predict  that  only  a  very  few  w^ould  remain  in  a  perfect  state  of 
preservation  for  one  year.  Several  canners  have  sent  us  cans  taken 
from  various  piles  and  these  we  have  placed  in  the  incubator  at 
98°  F.,  and  in  nearly  all  cases  the  cans  have  either  swelled  or 
turned  sour  after  a  few  days.  There  are  generally  two  different 
classes  of  organisms  responsible  for  this  spoilage.  One  class  be- 
longs to  the  anaerobic  species ;  that  is,  the  bacteria  are  able  to  grow 
only  where  atmospheric  oxygen  is  entirely  excluded  or  replaced  by 
some  other  gas.  These  germs  produce  large  quantities  of  gas 
which  is  malodorous,  being  a  combination  of  sulphuretted  hydro- 
gen, phosphoretted  hydrogen  and  methane.  The  pressure  of  this 
gas  in  the  cans  is  so  great  at  times  that  the  seams  burst,  the  ends 
blow  out  and  the  steel  sheet  is  rent.  Some  of  the  cans  sent  to  us 
arrived  entirely  empty,  the  contents  having  escaped  in  transit. 

The  other  class  of  germs  is  aerobic,  or  facultative  anaerobic. 
By  this  we  mean  the  bacteria  are  able  to  grow  in  an  environment 
devoid  of  oxygen  but  their  nature  is  to  grow  in  the  presence  of  oxy- 
gen. These  germs  produce  chemical  changes  in  the  peas  which  are 
far  rnore  dangerous  than  those  produced  by  the  other  kind,  from 
the  fact  that  they  do  not  form  any  gases  excepting  small  quantities 
of  sulphuretted  hydrogen,  which  is  absorbed  by  the  fluid  of  the 
contents.  Where  peas  are  spoiled  by  these  bacteria,  they  give  no 
evidence  of  the  fact  until  the  cans  are  opened.  The  liquor  is  gener- 
ally muddy  and  the  peas  are  intensely  acid.  The  natural  sugar  or 
carbohydrates  is  converted  into  simple  and  complex  fatty  acids. 
There  is  a  large  number  of  different  species  included  in  these  two 
classes  of  bacteria  just  described.  The  general  characteristics  of 
all  are  similar.  There  are  some  biological  or  morphological  dis- 
tinctions by  which  we  are  able  to  identify  them  and  note  the  peculiar 
changes  brought  about  in  the  certain  cans. 

The  following  letter  was  received  from  a  prominent  canner  of 
peas: 


PEAS.  389 

National  Canners'  Laboratory,  Aspinwall,  Pa. : 

GentIvEmen  : — We  are  sending  you  today  by  prepaid  express 
six  cans  of  new  pack  of  peas,  four  cans  from  early  pack  and  two 
cans  from  late  pack.  We  have  had  complaint  concerning  cloudy 
liquor  on  these  goods  and  we  would  like  you  to  inform  us  the  cause 
of  this,  etc. 

Hoping  to  hear  from  you  as  early  as  possible  and  thanking 
you,  we  remain.  Yours  very  truly, 


Wlien  these  peas  arrived  we  opened  them  carefully  and  ex- 
amined the  juice  under  the  microscope.  The  early  varieties  seemed 
to  be  the  only  ones  affected.  The  liquor  on  the  large  varieties  was 
perfectly  clear.  In  the  other  case  the  peas  were  very  much  broken 
and  the  protein  matter  was  cooked  up  with  the  juice  so  that  in  some 
cans  it  presented  the  appearance  of  pea  soup.  It  was  evident  to  my 
mind  that  these  peas  had  been  over-processed,  but  I  cannot  say 
what  process  was  used  because  none  is  mentioned  in  the  letters  re- 
ceived. There  are  several  conditions  from  which  may  result  muddy 
liquor  and  bursted  peas,  and  it  is  sometimes  difficult  to  know  just 
what  the  cause  is,  without  being  perfectly  familiar  with  every  step 
in  the  process  of  manufacture.  For  instance :  If  the  shelled  peas 
had  been  allowed  to  stand  for  any  great  length  of  time  in  baskets 
before  blanching,  it  is  quite  likely  that  the  skins  would  suffer  from 
the  action  of  bacteria.  We  know  that  certain  bacteria  have  the 
power  to  soften  fiber,  and  the  spores  of  this  very  species  are  al- 
ways present  on  the  skins  of  peas,  having  found  their  way  there 
in  the  machines  which  do  the  hulling.  Now,  in  case  shelled  peas 
were  allowed  to  stand,  even  over  night,  when  the  temperature  was 
quite  warm,  this  decomposition  of  the  fiber  would  likely  take  place. 
It  is  quite  easy  to  understand,  therefore,  that  the  skins  would  not 
be  able  to  withstand  the  pressure  ordinarily  given  peas  in  steriliza- 
tion; they  would  burst  and  cloud  the  liquor.  The  same  difficulty 
might  arise  from  peas  that  had  been  filled  into  the  cans,  if  the  cans 
were  allowed  to  stand  for  a  long  time,  on  account  of  breakdowns 
in  the  machinery,  or  overcrowding,  but  generally  this  bursting  of 
the  peas  is  due  to  over-processing.  This  case  was  so  extremely 
bad  that  there  is  little  doubt  of  this  solution  being  correct. 

As  we  stated  in  a  previous  chapter,  the  processing  should 
be  just  sufficient  to  keep  the  goods  without  danger  of  bursting  the 
peas  or  imparting  to  them  a  scorched  taste  or  odor.  If  a  proper 
chilling  apparatus  be  employed  and  alum  used  in  the  blanching  pro- 
cess to  toughen  the  skins  of  the  peas,  which  it  does  by  its  astringent 
properties,  there  will  be  very  little  danger  of  peas  bursting  or  hav- 
ing a  scorched  taste,  unless  the  sterilization  is  pushed  entirely  too 


390  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

far.  We  have  found  for  all  practical  purposes,  that  250°  for  20, 
25  and  30  minutes,  according  to  the  sizes,  will  generally  give  pretty 
good  results.  We  are  aware  that  this  process  may  be  reduced 
somewhat  in  certain  sections,  but  not  very  much,  without  great 
danger  of  spoilage. 

E.  W.  Duckwall,  Aspinwall,  Pa. 

D^AR  Sir  : — We  sent  you  some  days  ago  samples  of  peas  that 
we  cooked  16  minutes  at  240°.  These  vou  reported  as  being  all 
OK. 

We  are  sending  you  today  six  tins  of  peas,  three  that  are 
bulged  and  three  cooked  same  as  the  other  cans  sent  you.  Kindly 
advise  if  the  three  tins  bulged  are  swells  or  leaks,  also  if  the  three 
cans  that  appear  all  right  are  all  OK.  In  our  opinion  the  three 
cans  look  like  swells,  as  we  have  been  unable  to  detect  any  leak  in 
the  cans.  However,  there  may  be  in  the  figure  stamped  on  the  cap 
or  possibly  in  the  impression. 

Very  truly  yours. 


E.  W.  Duckwall,  Aspinwall,  Pa. 

Dear  Sir  : — Your  favor  of  the  9th  at  hand,  same  being  in  re- 
gard to  the  six  cans  of  peas  sent  you  Aug.  2d.  We  became  con- 
vinced shortly  after  we  sent  these  peas  that  we  had  swells.  We 
have  canned  peas  at  this  place  for  seven  3^ears.  We  have  several 
years  cooked  our  Alaska  peas  as  low  as  15  and  16  minutes  at  240. 
Our  sweet  wrinkle  peas  we  have  cooked  anywhere  from  18  to  22 
minutes  at  240,  and  we  never  have  had  any  swells  before.  Our 
Alaska  pack  this  year  were  all  cooked  18  minutes  at  240.  The  Ad- 
miral peas  this  year  we  cooked  nearly  all  at  240  for  18  minutes. 
We  cooked  a  small  amount  16  minutes  at  240.  The  first  cans  we 
sent  you  were  from  the  first  of  our  16  minute  cook,  and  these  you 
reported  free  from  bacteria.  Our  Alaska's  this  year  have  no 
swells  in  them.  We  have  now  nearly  completed  piling  our  Admiral 
peas  and  have  taken  out  about  10,000  swells.  The  small  sizes  seem 
to  have  more  swells  than  any  of  the  others,  the  third  sieve  or  what 
we  call  sifted  peas  having  the  most.  We  are  at  a  loss  to  know  how 
soon  it  would  be  safe  to  begin  shipping  from  these  goods,  and 
whether  swells  will  continue  to  show  up  in  the  goods  from  now  on. 
We  have  never  been  able  to  cook  peas  more  than  about  20  minutes 
at  240  and  get  a  clear  liquor.  Answering  your  question  as  to  a 
preservative,  would  say  that  we  have  never  used  any  in  our  peas. 

Yours  trulv, 


PEAS.  391 

VVe  were  very  much  surprised  on  reading  these  letters  that 
the  parties  had  processed  their  goods  successfully,  as  they  claim, 
for  a  number  of  years  at  240°  F.  for  only  16  to  18  and  22  min- 
utes, and  it  is  not  surprising  that  the  loss  is  so  great,  as  the  letter 
states  that  up  to  this  time  they  have  taken  out  about  10,000  swells. 


Plate  138 

Photograph  of  the  colonies  of  the  anaerobic  species  described  in  Plate  139. 
This  is  an  agar  slant  and  the  colonies  are  growing  on  the  surface.  The  rings 
are   easily   seen.     See   text.     Magnified   2   times. 

I  immediately  examined  the  two  cans  left  in  the  incubator  and 
found  one  of  them  swelled.  In  my  previous  letter  to  these  parties 
I  asked  them  if  they  had  used  any  preservatives.  1  did  not  make 
an  analysis  to  determine  if  preservatives  had  been  employed,  and 


Wate  139 

Photomicrograph  of  young  vegetating  rods  of  the  anaerobic  pea  bacillus  found 
in  can  of  swelled  peas.  It  forms  terminal  spores  in  three  days.  The  young  cul- 
tures are  actively  motile,  being  endowed  with  numerous  very  curly  flagella  so 
characteristic  of  anaerobic  varieties.  This  specimen  was  stained  with  difficulty. 
Magnified  1,000  diameters. 

this  was  unnecessary,  because  their  last  letter  states  that  none  had 
been  used.  I  wrote  these  parties  at  once  that  I  feared  their  spoil- 
age would  be  very  great,  because  I  did  not  see  how  it  would  be 
possible  to  keep  these  goods  from  spoiling  in  hot  weather. 


392  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

The  bacteria  which  are  usually  responsible  for  the  spoilage 
of  peas  grow  best  in  a  temperature  between  80°  and  98°  F.  It 
is  possible  to  reprocess  the  cans  at  240°  F.  for  fifteen  minutes..  All 
cans  which  have  started  to  spoil  will  swell  slightly  in  the  process 
and  the  ends  will  draw  in  slowly,  and  they  may  be  separated  from 
the  good.  All  cans  which  are  infected  with  only  a  few  bacteria 
can  be  saved  by  reprocessing.  I  set  about  to  determine  what  or- 
ganisms were  responsible  for  this  spoilage.  I  inoculated  several 
tubes  of  nutrient  bouillon :  also  several  test  tubes  of  agar  slants.  I 
also  streaked  the  surface  of  several  Petri  dishes  containing  nutri- 
ent agar.  Some  of  the  tubes  of  bouillon  I  sealed  in  the  anaerobic 
apparatus  and  produced  that  condition  by  means  of  Pyrogallic  acid 


^% 


H. 


't 


Plate  140 

Photomicrograph  of  the  spore  bearing  rods  of  the  anaerobic  pea  bacillus  found 
in  a  can  of  swelled  peas.  The  spores  are  terminal  and  greatly  resemble  B.  tetanus. 
This  photograph  shows  how  the  old  cells  dissolve  in  the  surrounding  fluid.  Mag- 
nified 1,000  diameters. 

and  a  weak  solution  of  sodium  hydroxid.  When  the  acid  and  the 
alkali  come  together,  all  the  oxygen  in  the  apparatus  is  absorbed, 
which  leaves  the  tubes  containing  bouillon  and  agar  in  an  anaerobic 
condition.  The  bouillon  became  cloudy  within  a  few  days.  Cloudi- 
ness in  the  bouillon  always  indicates  the  presence  of  bacteria.  Col- 
onies also  made  their  appearance  on  the  agar  slants.  These  we  ex- 
amined carefully  and  found  that  there  were  two  kinds.  One  kind 
was  an  obligative  anaerobe.  The  other. kind  was  a  facultative  an- 
aerobe. The  first  kind  is  able  to  grow  only  where  oxygen  is  en- 
tirely excluded;  the  second  kind  is  able  to  grow  in  the  presence  or 
absence  of  oxygen. 


PEAS.  393 

DESCRIPTION  OF  THE  COLONIES  OF  THE  ANAEROBES. 

The  colonies  were  round  and  scalloped;  of  a  brownish  color; 
the  surface  was  granular  and  there  was  a  light-colored  zone  form- 
ing a  ring  near  the  outer  edge.  This  was  seen  Avhen  magnified  60 
diameters.  The  natural  color  of  the  colony  was  white,  and  by 
transmitted  light  was  gray  with  a  blue  center,  white  periphery. 
The  surface  looked  moist  and  showed  a  distinct  bluish  colored  circle 
in  the  center.  Colonies  are  slightly  elevated,  measuring  from  3 
to  6  millimeters  in  diameter.  After  transplanting  to  other  slants, 
we  were  able  to  get  a  superficial  growth  of  these  bacteria,  and  to 
stain  them  for  flagella,  as  the  accompanying  plate  will  illustrate. 
The  flagella  are  organs  of  locomotion,  and  like  all  motile  anae- 


Plate 


This  is  a  photograpli  of  the  streak  growth  on  agar  in  Petri  dishes.  The  streaks 
were  made  up  and  down.  The  outgrowths  on  both  sides  are  characteristic.  No 
other  organism  has  a  growth  just  like  this.  This  growth  is  from  a  streak  made 
24  hours  previously  and  incubated  at  98  degrees   F. 

robes,  the  bacteria  are  very  much  curled.  In  various  views  of  the 
slides  which  we  stained  there  were  large  twisted  bodies,  which  are 
called  giant  whips.  Many  cultures  of  bacteria  have  the  faculty  of 
forming  giant  whips.  Just  what  these  bodies  are  has  not  been 
fully  established,  but  it  is  thought  that  they  are  formed  by  numer- 
ous flagella  which  have  fallen  away  from  the  germs  and  become 
twisted  together.  This  organism  produces  a  wonderful  amount  of 
gas,  having  a  distinct  odor  of  sulphuretted  hydrogen.  The  water 
of  condensation,  which  always  forms  at  the  bottom  of  an  agar 
slant,  fermented  very  freely  and  the  escape  of  gas  was  evident  by 
the  large  number  of  gas  bubbles.     We  grew  this  organism  in  milk 


394  CANNING  AND  PRESERVING  OP  FOOD  PRODUCTS. 


Bacillus  Mycoides 

On^m.— Widely  distributed  in  earth;  found  also  in  river  and  in 
spring  water. 

Form.—RcitheT  large  rods,  with  slightly  rounded  ends;  these  are 
thicker  than  the  hay  bacillus.     Threads  are  common. 

Motility. — It  has  a  slow  motion. 

Sporulation. — Forms  small  median  spores. 

Anilin  Dyes. — Stain  readily. 

Growth. — Rapid. 

Gelatin  Plates. — The  colonies  somewhat  resemble  fine  branching  root- 
lets. At  first  they  are  round  and  dark,  with  bristly  borders,  but  they  sub- 
sequently branch  out  through  the  gelatin,  which   is  slowly  liquefied. 

Stah  Culture.  This  is  characteristic,  the  growth  developing  along  the 
line  of  inoculation  and  from  this  threads  penetrate  or  radiate  into  the  sur- 
rounding gelatin.  The  growth  being  more  rapid  at  the  top  than  in  the 
lower  parts  of  the  tube,  the  result  is  that  it  has  the  appearance  of  an  in- 
verted pine  tree.  Subsequently  the  gelatin  is  completely  liquefied,  the 
bacterial  growth  accumulating  on  the  bottom  and  the  liquid  above  be- 
coming clear,  with  a  thin  scum  on  the  surface. 

Streak  Culture. — On  agar,  a  grayish  growth  is  formed  which  spreads 
outward  from  the  streak,  often  giving  it  an  appearance  resembling  the 
centipede.  On  potato,  it  forms  a  slimy,  whitish  growth  which  contains 
large  numbers  of  spores. 

Oxygen  Requirements. — Aerobic. 

Temperature. — It  will  grow  at  ordinary  temperature,  and  in  the  incu- 
bator. 

Behavior  to  Gelatin. — Liquefies  slowly. 

Pathogenesis.  It  has  no  effect,  not  even  in  large  doses.  Experiments 
are  now  being  made  on  patients  suffering  with  tubercle  bacilli  in  the  lymph 
system.  Pure  cultures  of  Bacillus  Mycoides  injected  into  the  lymph  glands 
seem  to  antagonize  the  multiplication  of  tubercle  bacilli. 


PEAS. 


395 


Plate  142 

Photomicrograph  of  a  slime  producing  bacillus  isolated  from  peas.  It  was 
slowly  motile,  able  to  grow  in  the  presence  or  absence  of  oxygen,  produces  acids 
without  formation  of  gas.  It  is  closely  allied  to  Bacillus  Mycoides.  Owing  to 
the  formation  of  slime,  the  fiagella  were  diflicult  to  demonstrate,  the  slime  was 
precipitated  with  chloroform,  and  the  fiagella  were  stained  with  a  mordant  and 
carbol  fuchsine.     Magnified  1,000  diameters. 


^^^:r. 


r  t^ 


•^•f 


Plate  143 


Photomicrograph  showing  rods  and  spores  of  the  bacillus  described  undei 
Plate  142,  a  facultative  anaerobic  germ  isolated  from  canned  peas.  The  spores 
are  extremely  small  and  located  at  the  center  of  the  rods.  Stained  by  carbol 
gentian  violet.    Magnified  1,500  diameters 


396  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

made  blue  by  tincture  of  litmus,  and  within  24  hours  the  litmus 
had  turned  red  and  the  milk  became  curdled.  After  24  hours  more 
the  curd  was  dissolved  and  a  heavy  precipitate  formed  at  the  bot- 
tom of  the  tube.  These  organisms  formed  large  terminal  spores 
and  grow  more  freely  than  the  Butyric  Acid  bacilli,  so  named  by 
Prazmowski.  The  spores  of  these  bacteria  were  quite  resistant  to 
heat.  They  are  able  to  withstand  a  temperature  of  240°  F.  for 
about  10  minutes  in  test  tubes,  and  in  No.  2  cans  of  peas  are  not 
destroyed  under  25  to  30  minutes  at  240°  P.  We  were  able  to  pro- 
duce some  swelling  of  the  cans  in  peas  that  we  had  in  the  labora- 
tory by  inoculating  cans  with  the  spores.  The  germs  do  not  grow 
well  at  ordinary  temperature  of  50°  to  70°  F.,  and  do  not  grow  at 
all  between  35  °  and  45°  F. 

DEJSCRIPTION  01?  THE  AE:rOBTC  VARIETY. 

The  aerobic  variety  seems  to  correspond  pretty  closely  with 
bacillus  mycoides.  The  colonies  were  round,  and  of  a  bluish  trans- 
parent cast.  Under  the  microscope  the  edges  are  slightly  scalloped ; 
a  smooth  center,  slightly  yellow,  becoming  thin  and  transparent  at 
the  periphery.  The  natural  size  of  the  colon}^  is  about  i  to  4  milli- 
meters; extremely  slimy,  so  that  a  needle  dipped  into  the  colony 
will  carry  a  slimy  thread  for  several  inches  on  removal.  We  had 
a  great  difficulty  in  demonstrating  the  flagella.  In  this  respect  the 
germ  resembles  Bacillus  Mycoides.  The  streak  on  agar  developed 
quite  rapidly  and  grew  down  into  the  medium.  Along  the  center 
scaly  folds  would  form  and  from  the  edges  would  be  distinct 
branches  typical  in  every  way  of  the  Root  Bacillus.  Its  identity 
therefore  is  established  somewhere  between  Bacillus  Vulgatus  and 
Bacillus  Mycoides.  We  stained  the  flagella  with  difficulty.  We 
took  the  growth  as  young  as  possible,  but  were  unable  to  get  any 
preparation  entirely  free  from  slime.  Some  writers  have  declared 
that  Bacillus  Mycoides  has  no  flagella  or  organs  of  locomotion,  and 
after  several  futile  attempts  to  demonstrate  their  presence  by  the 
regular  method,  it  seemed  probable  that  the  flagella  were  absent. 
In  hanging  drop  cultures,  however,  we  could  see  that  the  bacilli 
were  motile,  having  distinct  serpentine  and  oscillating  motion.  On 
every  cover  glass  the  slime  would  form  a  very  thin  layer,  suffi- 
ciently heavy,  however,  to  obliterate  the  flagella,  so  we  adopted  an- 
other method  of  staining.  We  inoculated  one  cubic  centimeter  of 
water  with  a  young  culture;  then  added  one  cubic  centimeter  of 
chloroform,  agitating  the  two  together  for  some  time.  The  chloro- 
form dissolved  the  slime  and  carried  it  down  to  the  bottom.  From 
the  water  above  the  chloroform  we  were  able  to  get  some  very  fair 
preparations  for  flagella  staining.  The  accompanying  plate  shows 
the  result  of  this  work.     This  organism  has  a  very  small  spore 


PEAS.  397 

centrally  located  in  the  rods.  When  growing  in  peas  there  is  no 
formation  of  gas.  The  carbohydrates  are  decomposed  into  fatty 
acids.  A  small  quantity  of  H2S  or  sulphuretted  hydrogen  is 
formed,  but  not  enough  to  cause  swelling  of  the  cans.  The  spores 
of  these  bacilli  are  more  resistant  to  heat  than  the  former  organism, 
and  are  therefore  more  inimical  from  the  fact  that  complete  chemi- 
cal decomposition  may  take  place  without  being  apparent.  The 
can  will  look  perfectly  natural  and  will  not  spring,  this  showing  that 
the  vacuum  is  still  present. 


398  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

CHAPTER  XIIL 

Tomatoes 

Character  of  Tomatoes  Raised  in  Different  Localities.  Method  of 
Canning.  Cold  Packed  Tomatoes.  Suggestions.  Laboratory 
Work.  Various  Bacteria  Found  in  Leaky  Cans  of  Tomatoes. 
Sour  Tomatoes  Due  to  Souring  Before  the  Sterilizing  Process; 
the  Cause  and  Remedy.  An  Attempt  to  Pack  Tomatoes  in  a 
Vacuum  Jar  Without  Sterilization ;  Cause  of  the  Spoilage.  Bac- 
teria the  Cause  of  Tomato  Black-rot  Disease.  Uneven  Tempera- 
ture in  the  Process,  Resulting  in  Loss. 


Tomatoes  raised  in  one  locality  differ  very  much  in  character 
from  those  raised  in  another  locality.  The  tomatoes  raised  in  our 
northern  states  are  more  meaty  and  contain  more  sugar  than  those 
raised  in  the  Valley  of  the  Mississippi  and  the  extreme  eastern  coast 
of  the  United  States.  The  sweeter  tomatoes  are  the  best  for  can- 
ning purposes,  while  for  making  tomato  catsup,  chili-sauce  and 
other  condiments  of  this  character,  those  which  contain  more  acid 
are  more  desirable. 

It  is  difficult  to  say  at  what  date  the  canning  of  tomatoes  in 
this  country  can  be  set  down  accurately.  There  is  a  record  of  Wil- 
liam Underwood  having  canned  tomatoes  in  glass  as  far  back  as  the 
year  1820,  but  the  business  did  not  grow  to  any  considerable  extent 
until  about  1875-80.  There  were  a  few  scattered  factories  canning 
tomatoes  between  the  years  i860  and  1875,  most  of  them  in  the 
neighborhood  of  Baltimore.  The  peeling  of  tomatoes  was  done  by 
hand  and  there  have  been  no  machines  perfected  for  this  work  up  to 
this  day.  The  filling  of  tomatoes  into  cans,  capping,  tipping,  etc., 
were  done  by  hand.  Today  most  of  the  filling  is  done  by  machinery 
and  the  capping,  of  course,  is  put  through  rapidly  by  the  automatic 
capping  machines. 

Probably  the  best  means  of  canning  tomatoes  is  by  what  is 
known  as  a  "cold  process,"  that  is  to  say,  the  tomatoes  are  filled  into 
the  cans  after  they  are  peeled  and  are  not  heated  prior  to  the  final 
sterilizing  process.  The  old  style  of  canning  tomatoes  was  to  fill 
the  cans,  then  give  them  a  heating  in  boiling  water  with  the  vents  of 
the  caps  open;  afterward  they  were  removed  and  the  vent  holes 
soldered  up,  and  then  the  cans  were  subjected  to  a  sterilizing  process 
of  about  thirty  minutes  at  212°  F. 


TOMATOES.  399 

Tomatoes  are  not  difficult  to  keep;  all  that  is  required  is 
rapidity.  This  is  absolutely  necessary  if  one  desires  to  can  cold- 
packed  tomatoes.  They  must  be  worked  up  very  rapidly  so  that  no 
bacteria  will  start  fermentation.  Fermentation  of  tomatoes  may 
be  due  to  several  kinds  of  micro-organisms,  but  principally  to  wild 
yeast  molds,  acetic  acid,  and  lactic  acid  bacteria.  In  this  process  of 
decomposition  there  is  a  gas  liberated,  carbon  dioxid.  If  this  gas 
is  liberated  in  any  quantity,  it  will  prevent  the  cans  from  collapsing 
after  the  sterilizing  process.  In  this  case,  it  would  be  impossible  to 
turn  out  fine  goods  unless  the  cans  were  vented.  I  would  like  to  im- 
press this  point,  namely,  that  if  cold-packed  tomatoes  are  to  be 
produced,  there  must  be  absolutely  no  fermentation  of  the  tomatoes 
in  any  process  prior  to  sterilization.  Fermentation  sets  in  very 
rapidly  after  the  tomatoes  are  peeled,  particularly  in  weather  where 
the  thermometer  registers  between  80°  and  90°  F.  They  will  fer- 
ment sometimes  in  the  buckets  of  the  peelers,  especially  where  the 
peeler  is  rather  slow  in  turning  out  her  work.  It  is  better  to  have 
small-sized  buckets  for  the  peelers  and  then  keep  the  tomatoes 
worked  up  very  closely. 

Much  depends  on  the  scalding  apparatus.  If  the  tomatoes  are 
not  properly  scalded,  fermentation  is  much  more  likely  to  follow 
than  if  the  outside  of  the  tomato  simply  is  scalded.  If  the  water 
is  not  kept  at  least  212°  F.  the  tomatoes  will  be  cooked  through  to 
the  center.  To  simply  scald  the  outside  of  the  tomato,  leaving  the 
inside  cool,  is  the  ideal  method  of  loosening  the  peels.  In  the  steril- 
izing process,  cold-packed  tomatoes  can  be  kept  all  right  with  a 
process  of  35-40  minutes  at  212°  F.  As  a  rule,  the  packer  can 
judge  whether  his  tomatoes  are  perfectly  sterilized  by  examining 
the  seeds.  There  is  a  gelatinous  envelope  around  the  seed  in  raw 
tomatoes  and  the  cooking  must  be  sufficiently  prolonged  to  loosen 
this  envelope.  We  have  seen  the  seeds  from  canned  tomatoes 
planted  and  some  of  them  sprouted.  All  such  canned  tomatoes  will 
swell ;  sometimes  when  no  bacteria  are  present,  there  will  be  suffi- 
cient evolution  of  carbonic  acid  gas  from  the  seeds  themselves  to 
cause  the  spoiling  of  the  goods.  Tomatoes  are  acid  by  nature  and 
cans  made  for  them  must  be  well  soldered.  The  smallest  possible 
leak  in  the  can  will  be  much  enlarged.  In  some  cases  where  there 
is  no  leak  at  first  the  solder  may  be  strained  in  the  sterilizing  pro- 
cess or  by  rough  handling,  and  the  acid  juice  of  the  tomato  will 
work  through.  A  great  many  of  the  spoilage  cases  of  tomatoes 
submitted  to  the  laboratory  were  due  to  leaks.  In  the  following 
pages  we  will  give  some  cases  in  detail. 

The  year  1903  was  the  largest  in  the  history  of  the  canning 
business  for  tomatoes,  the  packing  amounting  to  ten  and  one-half 
million  cases. 


400  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

A  canner  wrote  as  follows :  "We  have  a  condition  this  year 
with  our  tomato  pack  that  we  have  never  had  before,  and  we  are 
trying  to  locate  the  cause.  Nine-tenths  of  them  seem  to  be  all  right, 
but  about  one  in  every  ten  is  sour,  a  fermented  sour,  but  the  can  is 
not  swelled  in  the  least.  They  cannot  be  located  without  cutting 
the  can.  Can  you  tell  us  the  cause  and  give  us  a  remedy;  and  is 
there  any  danger  of  the  per  cent  getting  larger  when  warm 
weather  sets  in  ?  We  are  sending  you  today  a  case  of  the  tomatoes 
that  we  told  you  were  sour  without  any  cause  that  we  could  de- 
termine.    There  are  only  about   lo  or  20  per  cent  of  them  sour. 


Plate  144 

Photomicrograph  of  Bacillus  Acidi  Aceti  or  Mycoderma  Aceti  or  "Mother  of 
Vinegar,"  showing  short  dumb-bell  rods,  large  lemon  shaped  and  drumstick  in- 
volution forms.  Produced  acetic  acid  in  tomatoes;  isolated  by  plate  culture 
method;  stained  with  fuchsine  and  mounted  in  xylol  balsam.  Magnified  1,000  diam- 
eters. 

The  can  that  is  wrapped  in  tissue  is  one  that  we  opened  and  found 
to  be  sour,  and  then  sealed  it  again.  We  have  had  canned  tomatoes 
here  for  years  and  have  never  seen  anything  like  it  before.  We 
do  not  know  the  cause.  As  we  put  up  a  pack  of  8,000  cases  and  as 
we  kept  no  record  of  each  day's  pack,  it  would  be  hard  to  tell  just 
what  were  the  exact  conditions  under  which  the  case  which  you  got 
were  packed,  but  I  think  I  can  tell  you  near  enough  what  the  condi- 
tions were  all  through,  so  you  can  determine  what  is  the  matter.  The 
sample  you  got  was  taken  from  the  early  packing,  where  most  of 
the  trouble  seems  to  be.  The  tomatoes  as  they  came  in  were  quite 
ripe,  and  sometimes  they  would  stand  on  the  platform  in  crates  for 


TOMATOES.  401 

two  or  three  days,  but  they  seemed  to  be  in  good  condition,  i.  e., 
tliere  were  not  any  rotten.  They  were  scalded,  peeled  and  put  into 
cans  reasonably  quick.  At  times  I  presume  there  were  tomatoes 
that  stood  for  30  minutes  after  they  were  peeled  before  they  were 
put  into  the  can.  I  hardly  think  that  they  ever  stood  longer  than 
30  minutes,  as  we  were  afraid  to  let  them  stand  around  after  they 
were  peeled.  There  were  very  few  that  stood  longer  than  fifteen 
minutes  before  they  were  put  into  the  can.  At  times  leaks  would 
be  allowed  to  stand  for  an  hour  or  two  before  repairing.  I  notice, 
however,  that  there  are  sours  among  those  that  were  never  patched. 
We  processed  30  minutes  in  water  at  the  boiling  point,  but  it  may 
be  possible  that  the  water  got  below  boiling  point  sometimes,  al- 
though we  were  careful  about  keeping  the  water  hot. 


When  the  samples  of  souf  tomatoes  arrived  we  found  that  quite 
a  number  of  cans  were  simply  cap  and  tip  leaks,  but  there  were  other 
cans  which  were  very  sour,  yet  showed  no  signs  of  leaks.  We 
made  bacteriological  tests  of  all  the  cans  which  appeared  to  be 
sound,  and  in  no  case  did  we  find  any  living  bacteria  in  these  cans. 
From  the  leaky  cans,  however,  we  isolated  two  kinds  of  bacteria 
which,  when  transplanted  into  good  cans  produced  the  same  acids 
and  aromatic  flavors  peculiar  to  the  sour  cans  of  tomatoes,  showing 
that  the  conditions  around  the  factory  were  such  as  to  endanger 
the  goods  at  all  times. 

The  liquid  in  some  of  the  leaky  cans  had  turned  to  vinegar, 
and  this  had  been  attached  by  another  organism,  which  we  shall 
presently  describe.  The  acetic  acid  bacteria  are  little  rods  having 
a  slight  constriction  in  the  middle,  giving  them  a  dumb-bell  shape 
when  highly  magnified.  These  bacteria  are  subject  to  complete 
change  of  form  and  this  peculiarity  is  technically  called  involution 
form.  Plate  144  will  show  examples  of  all  forms  from  the  small 
typical  rods,  to  swelled  lemon  shaped,  club  shaped  and  other  forms 
so  frequently  seen  in  the  mycoderma  aceti  or  "mother  of  vinegar." 
\\'hen  these  germs  are  alone  in- their  vv^ork,  only  acetic  acid  is 
formed,  but  when  other  organisms  are  present  the  acetic  acid  is 
changed  and  flavored  with  unpleasant  aromatic  substances,  such  as 
volatile  fatty  acids  and  ethers. 

W^e  isolated  a  chromogenic  bacillus,  which  produced  a  reddish 
violet  pigment  in  the  agar.  When  transplanted  into  tomato  juice 
it  produced  a  deep  red  color  and  formed  a  pellicle  on  the  surface. 
It  is  a  slowly  motile  organism  with  very  fine  flagella,  running  out 
in  gentle  curls  from  the  whole  surface  of  rod.  Our  plate  is  magni- 
fied about  2,000  diameters  and  this  is  about  four  million  times  mag- 
nified. 


402  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

From  the  pellicle  we  obtained  the  spores  of  the  bacillus  and 
were  not  able  to  destroy  them  by  boiling.  They  do  not  grow 
readily  on  pure  tomatoes  and  seem  to  demand  acetic  acid  to  get  a 


y 


i  \ 


< 


/» 


Plate  145 

Photomicrograph  of  Bacillus  X,  a  chromogenic  motile  bacillus,  isolated  from 
a  can  of  spoiled  tomatoes  where  the  acetic  acid  bacteria  were  also  present.  It 
has  numerous  hair  like  flagella  and  moves  in  a  slow  wabbling  motion.  It  pro- 
duced a  dark  red  pigment.  Stained  by  our  special  method,  from  Agar  culture 
very  young.     Magnified  2,000  diameters. 

start,  SO  this  accounts  for  their  not  being  generally  found  on  toma- 
toes unless  other  organisms  have  worked  out  chemical  changes,  or 
produced  substances  favorable  for  their  propagation.  If  we  had 
to  contend  with  this  bacillus  generally,  our  tomatoes  would  require 


•           • , 

\.M*          *  ^ 

*    *           .•     .       ♦ 

a# 

*     ♦  •*-   .     i 

«,       •  «      "  #            0 

- . 

#^         *•  '          .            •      , 

«  '4 

«iM!»  « 

.   * 

•    ■.'  A      * 

*     -l-i     . 

^ 

*J- 

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,■;•»  .■'••,, 

W 

■f  ^    ' 

Plate  146 

Photomicrograph.— Spores  and  rods  of  Bacillus  X,  isolated  from  sour  toma- 
toes. The  whole  rod  seems  to  become  a  spore,  the  cell  contents  are  apparently 
surrounded  by  the  cell  membrane  almost  the  entire  length.  This  afterwards  con- 
tracts and  an  oval  spore  is  set  free.  Stained  with  carbol  fuchsine.  Magnified 
1,000  diameters. 


TOMATOES.  403 

250  degrees  F.  for  perhaps  25  minutes  to  destroy  the  spores.  This 
would,  of  course,  cook  the  tomatoes  too  much  and  it  would  be  a 
problem  to  successfully  pack  them.  If,  however,  we  observe  the 
rule,  to  work  up  the  raw  material  as  fast  as  it  is  received,  we  need 
have  no  fear  of  this  difficulty. 

CONCLUSIONS. 

After  investigating  carefully  the  samples  of  sour  tomatoes 
sent  me  I  submit  my  report.  There  are  quite  a  number  of  leaks 
among  the  cans  in  the  capping  and  tipping.  There  are  no  living 
bacteria  in  any  of  the  good  cans  or  the  cans  which  are  sour,  except- 
ing the  leaks,  therefore  there  will  be  no  further  souring  of  the  goods. 
The  sour  tomatoes  were  sour  before  they  were  processed,  probably 
before  they  were  scalded,  the  acid  having  formed  in  them  and  still 
remains  in  the  finished  goods.  I  would  advise  you  to  work  your 
tomatoes  up  quickly,  or  if  unable  to  do  this  at  all  times,  provide  a 
way  to  make  them  into  tomato  pulp  for  catsup,  etc.  If  you  have 
much  trouble  with  breakdowns,  try  and  make  such  improvements 
in  your  mechanical  apparatus  as  will  preclude  the  possibility  of  sour- 
ing. Have  your  scalding  water  boiling  hot — that  is,  hot  enough 
to  scald  the  skins  off  the  tomatoes  and  still  leave  the  inside  of  the 
fruit  cool.  In  this  way  you  will  avoid  souring  after  the  peeling, 
to  a  great  extent.  I  met  with  a  case  similar  to  this  one  in  1891 
which  lead  me  to  take  up  the  study  of  bacteriology  in  connection 
with  canning. 

If  you  have  any  doubts  of  your  sterilizing  apparatus,  look  into 
the  matter  carefully  and  arrange  your  system  in  such  a  way  that 
no  mistakes  will  be  made  at  that  point  next  season.  This  case  has 
nothing  to  do  with  sterilization;  the  souring  occurred  before  the 
tomatoes  reached  the  process.  I  want  to  call  your  attention  again 
to  poor  soldering,  and  would  advise  you  to  take  steps  to  improve 
in  that  work.  A  great  deal  of  your  spoilage  is  no  doubt  due  to 
imperfect  work. 

TOMATOKS   PACKED   IN    A  VACUUM    JAR. 

The  sample  of  spoiled  Tomatoes  was  fermenting  and  the  es- 
caping gas  had  made  an  opening  through  the  wax.  A  microscopi- 
cal examination  of  the  juice  showed  large  numbers  of  yeast-like 
forms  which  we  mounted  on  a  slide.  Plate  147  illustrates  their  ap- 
pearance. The  dark  cells  are  the  oldest,  and  from  these  others 
have  grown  out  from  all  sides,  first  making  their  appearance  as 
very  small  excrescences,  then  gradually  filling  out,  soon  attain  the 
same  size  and  appearance  as  the  mother  cell,  and  in  like  manner 
these  give  rise  to  buds  as  before,  until  quite  a  little  bunch  will  be 
seen  en  masse. 


404 


CANNING  AND  PRESERVING  OP  FOOD  PRODUCTS. 


In  order  to  determine  just  what  these  were  we  streaked  a 
number  of  Petri  dishes  containing  tomato  agar.  Tomato  agar  is 
simply  filtered  tomato  juice  to  which  one  and  one-half  per  cent  of 
Agar-agar  has  been  added  to  make  a  solid  culture  medium  or  jelly 


OO       f^ 


Plate  147 

Photomicrograph  of  the  building  Conidia  of  Mucor  Mucedo,  obtained  from  a 
jar  of  spoiled  tomatoes  undergoing  fermentation.  These  conidia  have  the  power 
of  setting  up  a  fermentation  similar  in  many  respects  to  that  of  the  yeasts.  In 
this  manner  of  growth  Mucor  Mucedo  looks  very  much  like  the  brewers'  yeast 
Saccharomyces  cerevisiae.     Magnified  1,000  diameters. 


Plate  148 

Photograph  of  a  Petri  dish  which  had  been  streaked  with  the  juice  of  fer- 
menting tomato.  The  moss-like  growths  are  the  Mucor  Mucedo  growing  in  pres- 
ence of  atmospheric  oxygen.  The  large  round  spots  are  motile  bacteria  growing 
in  colonies.  The  small  round  spots  are  Acetic  Acid  Bacteria  in  colonies.  This 
is  the  method  we  employ  to  isolate  the  various  bacteria  found  in  spoiled  goods. 
The  Petri  dish   contains  a  medium   of  tomato  juice   and  Agar  jelly. 


culture.  In  two  days  our  dishes  had  very  good  growth,  and  Plate 
148  will  illustrate  their  appearance.  The  moss-like  growths  are 
mycelia  of  the  mold  plant  Mucor  Mucedo,  which  is  a  fungus  belong- 
ing to  the  order  of  Hyphomycetes,  a 


igher  type  in  the  botanical 


TOMATOES. 


405 


classification  than  the  bacteria.  The  round  dark  spots  are  colonies 
of  bacteria,  which  we  will  describe  later  on.  Plate  149  is  a  mag- 
nification of  Plate  148  of  about  four  diameters,  showing  more  dis- 
tinctly the  moss-like  growth.     The  very  small  dark  spots  through- 


'W^' 


Plate  149 

Photograph  of  Plate  No.  148  magnified  four  times.  In  the  moss  like  growths 
of  the  mold  Mucor  Mucedo  there  are  a  number  of  very  small  dark  spots.  These 
are  the  first  pods  which  are  borne  on  very  delicate  hair-like  stocks.  The  round 
pods  contain  the  little  seed  forms  called   conidia,  which  are  shown  in   Plate  147. 

out  the  moss-like  growths  are  the  fruit  pods,  which  grow  on  very 
slender — hair-like — stems  or  sporangia.  There  are  a  large  num- 
ber of  these,  which  soon  attain  a  height  of  an  inch  or  more  under 
favorable  conditions,  and  at  the  top  of  each  is  a  small  round  pod 
or  cell  which  contains  a  vast  number  of  tiny,  round,  shot-like  seeds, 
called  conidia,  each  one  of  which  is  able  to  start  a  new  mold  plant. 


406  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

Plates  150  and  151  are  good  illustrations  of  the  microscopical 
appearance  of  these  cells  containing  seeds  conidia,  under  a  magni- 
fication of  800  diameters.  These  very  delicate  forms  of  vegetable 
life  are  so  tender  and  sensitive  that  we  cannot  stain  and  mount 
them  in  the  usual  manner,  consequently  the  photography  is  quite 
difficult,  since  they  must  be  mounted  alive  in  glycerine,  fixed  with- 
out heat,  and  unstained.  The  Mucor  is  almost  transparent,  and 
consequently  a  negative  giving  good  contrast  cannot  be  obtained. 
In  the  two  plates  we  have  part  of  the  mycelium  very  much  inter- 
laced, as  it  is  naturally,  and  scattered  throughout  are  the  round 
fruit  pods  containing  the  seed  or  conidia. 


Plate  150 

Photomicrograph  of  Mucor  Mucedo  in  the  living  state,  mounted  in  glycerine. 
The  round  pod  in  the  center  contains  the  seed  forms  or  conidia.  This  pod  is 
ripe,  ready  to  burst  when  the  conidia  are  carried  by  water  or  air,  ready  to  start 
a  new  mold  plant  or  to  set  up  fermentation  according  to  the  conditions  in  which 
they  are  thrown.     Magnified  800  diameters. 

The  conidia  have  peculiar  morphological  characteristics,  being 
able  to  assume  two  distinct  biological  characters  marked  by  the  man- 
ner of  their  reproduction  and  the  chemical  changes  wrought,  es- 
pecially when  compelled  to  live  in  a  partial  or  complete  anaerobic 
environment.  In  this  condition  their  appearance  and  vegetation  re- 
semble the  Blastomycetes  or  yeasts  so  closely  that  differentiation  is 
difficult,  unless  we  resort  to  the  plate  culture  method,  as  was  done 
in  this  case.  Plate  147  illustrates  the  growth  of  Mucor  Mucedo 
when  submerged  in  nutrient  tomato  juice,  where  its  supply  of  at- 
mospheric oxygen  is  cut  off,  while  Plates  148  and  149  show  the 
natural  growth  when  the  conidia  are  able  to  obtain  oxygen  from  the 
atmosphere. 

When  growing  in  an  anaerobic  condition  the  supply  of 
oxygen  (which  mold  demands  in  large  quantities)  is  obtained  from 
the  various  molecules  of  vegetable  matter,  and  the  carbohvdrates. 


TOMATOES.  407 

setting  free  carbonic  acid  gas  in  considerable  volume,  by  which  re- 
action, alcohol,  succinic  acid,  glycerin,  volatile  fatty  acids  and  others 
are  formed,  which  in  their  turn  are  attacked  by  various  kinds  of  bac- 
teria, most  commonly  by  the  acetic  acid  group,  but  frequently  by 
motile  putrefactive  organisms,  which  produce  disagreeable  aromatic 
compounds. 

In  Plates  148  and  149,  we  notice  the  dark  round  spots  among 
the  mold  filament.  There  are  colonies  of  bacteria,  and  there  are 
two  kinds,  one  of  which  is  the  acetic  acid  bacillus,  described  prev- 
iously. Plate  153  is  a  bacillus  much  resembling  Megather- 
ium in  its  spore  formation  and  the  arrangement  of  its  flagella  or 


Plate  151 

Photomicrograph  of  Mucor  Mucedo,  showing  the  seed  pods  containing  the 
conidia.  These  pods  are  not  yet  ripe,  consequently  the  conidia  are  not  yet  per- 
fectly formed.  This  specimen  is  living  and  mounted  in  glycerin  for  microscopical 
examination.     Magnified  800  diameters. 


\ 


\ 


/ 


\ 

I 


Plate  15; 


Photomicrograph  of  the  Tomato  Bacillus,  a  slowly  motile,  aromatic  bacillus, 
which  destroys  tomatoes  by  the  unpleasant  flavor  it  produces.  This  specimen  was 
obtained  from  a  young  growth  on  tomato  agar,  and  the  demonstration  of  the 
flagella  was  done  by  author's  special  staining  method.     Magnified  1,000  diameters. 


408 


CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


organs  of  locomotion,  but  far  more  difficult  to  stain.  The  spore 
formation  is  peculiar,  as  shown  in  Plate  154.  The  spore  occupies 
nearly  the  whole  length  of  the  cell,  but  gradually  becomes  smaller 
as  the  cell  membrane  is  dissolved  in  the  surrounding  fluid.  After 
this  organism  has  done  its  work,  the  tomato  juice  has  such  a  disa- 
greeable odor  that  nothing  can  be  done  with  it.  Ordinarily,  to- 
matoes which  have  simply  undergone  fermentation  may  be  made 
mto  very  good  catsup,  but  not  the  best  quality. 


BI.ACK  ROT  O^  TOMATOES. 


We  received  by  express  a  tomato,  one  side  of  which  was  com- 
pletely diseased  by  what  is  known  as  black  rot  disease,  and  the 
following  letter  will  explain: 


Plate  153 

Photograph  of  the  Tomato  Bacillus,  as  shown  in  Plate  142.  The  spores  are 
quite  long  when  forming  within  the  rods,  occupying  nearly  the  whole  cell.  After 
being  set  free  they  become  smaller  and  the  membrane  becomes  thicker.  Stained 
with   carbol    fuchsine   mounted    in   Xylol    Balsam.     Magnified    1,000   diameters. 

"J  send  you  under  separate  cover'  sample  green  tomato.  A 
great  many  of  the  tomatoes  on  our  vines  present  the  same  appear- 
ance as  this  sample.  Is  this  not  caused  by  the  tomato  louse?  Your 
opinion  will  be  appreciated." 

The  cause  of  the  black  rot  is  not  due  to  the  tomato  louse,  as 
the  letter  suggests,  but  to  a  bacterium.  We  made  cultures  of  this 
organism  from  the  tomato,  and  were  successful  in  getting  fine 
growths  on  nutrient  agar  in  Petri  dishes.  In  order  to  be  certain 
that  our  culture  was  the  right  organism,  we  inoculated  several  to- 


TOMATOES. 


4U9 


matoes  with  a  loop  full  of  the  bacteria  from  the  pure  culture,  and 
were  successful  in  transplanting  the  disease.  We  found,  however, 
that  we  could  not  communicate  the  disease  to  perfect  tomatoes  with- 
out puncturing  the  skin.  When  the  bacteria  were  simply  spread 
over  the  surface  of  the  skin,  they  remained  dormant  or  dried  up 
without  inducing  the  disease.  We  are  at  a  loss,  however,  to  know 
how  to  apply  a  remedy  for  the  black  rot  in  the  patch  of  tomatos. 
We  have  noticed  that  this  disease  is  more  frequent  in  either  ex- 
tremely dry  or  in  extremely  wet  weather.  In  dry  weather  the  toma- 
toes are  frequently  attacked  by  insects  and  the  bacteria  which  are  re- 
sponsible for  black  rot  thus  gain  an  entrance  through  the  perforated 
skin.  Sometimes  after  a  rain  the  sun  will  come  out  very  brightly 
and  the  skins  will  crack  open  under  the  influence  of  the  heat,  thus 
affording  a  means  of  invasion  by  bacteria. 


Plate  154 
Photomicrograph    of   Bacillus   Acidi   Aceti    or    Myeoderma   Aceti    or    "Mother    of 
Vinegar,"    showing   short   dumb-bell   rods,    large   lemon-shaped   and    drumstick,    in- 
volution forms.     Produced  acetic  acid  in  tomatoes;   isolated  by  plate  culture  meth- 
od; stained  with  fuchsine  and  mounted  in  xylol  balsam.    Magnified  1,000  diameters. 

In  extremely  wet  weather  tlie  plants  are  sometimes  knocked 
down  and  the  tomatoes  rest  on  the  wet  ground  where  they  are  at- 
tacked by  worms  and  various  insects  and  bacteria  may  set  up  the 
disease  through  the  perforations  thus  made  in  the  skin.  The  black 
rot  disease  sometimes  works  its  way  entirely  through  the  tomato,  de- 
stroying it.  Frequently  only  a  portion  is  affected,  and  this  is  re- 
moved, of  course,  when  the  tomatoes  are  peeled.  When  tomatoes 
are  intended  for  catsup,  all  such  diseased  places  have  to  be  cut  with 
a  knife,  because  black  rot  disease  will  permeate  the  whole  batch  of 
pulp,  and  black  specks  in  the^^Dd§,aiull  result.     While  we  are  not 

OF  THE 


410  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

able  to  suggest  any  means  of  destroying  the  bacteria  which  are  re- 
sponsible for  such  widespread  destruction  of  tomatoes  as  we  some- 
times see,  it  is  interesting  to  know  just  what  organisms  are  responsi- 
ble, and  gives  us  a  means  of  studying  the  problem  of  overcoming 
these  losses.  The  accompanying  plate  gives  a  microscopic  view  of 
the  black  rot  bacilli  as  they  appear  when  magnified  1,200  diameters. 
The  colonies  of  this  germ  are  of  a  slightly  yellow  color,  even 
bordered.  The  streak  culture  on  agar  is  somewhat  lustrous  and 
yellowish  in  color,  after  a  time  becoming  darker,  deepening  into  al- 
most a  brown.  The  organisin  is  not  motile,  and  so  far  as  we  were 
able  to  study  its  characteristics,  it  does  not  form  spores.  We  in- 
tend to  study  the  morphological  and  biological  characteristics  of 
the  tomato  black  rot  bacillus,  and  endeavor  to  find  some  means  of 
protecting  the  maturing  tomatoes  in  the  patch  when  this  disease  is 
rampant. 


#  *^* ;" 


Bacillus  of  Tomato  Black  Rot  disease.  This  is  not  a  motile  organism,  and 
no  spores  have  been  observed.  This  is  a  photomicrograph  obtained  from  a  fuch- 
sine  stained  preparation  of  pure  culture  of  the  bacilli  on  Agar.  Magnified  1,200 
diameters. 

A  case:  o^  leaky  cans. 

The  case  of  tomatoes  arrived  at  the  laboratory  and  a  pretty 
thorough  examination  was  made  of  every  can  and  particularly  the 
solder.  Some  of  the  solder,  when  viewed  through  a  sixteen  milli- 
meter objective,  had  a  honeycombed  appearance.  Solder  made  in 
the  proportion  of  thirty  tin  and  seventy  lead  is  not  fit  for  either  can 
making,  capping  or  tipping.     Solder  used  in  can  making  ought  to 


TOMATOES.  411 

be  about  half  and  half  and  that  used  for  capping  and  tipping  forty 
tin  and  sixty  lead.  Solder  made  with  seventy  per  cent  lead  would 
necessarily  be  much  weaker  than  that  which  contained  a  greater  per 
cent  of  tin,  and  then  again  such  solder  is  liable  to  impart  traces  of 
lead  to  the  canned  product.  A  complete  report  of  these  cans  is 
here  appended : 

l^IRST   CAUSE  01?  ALIv   SPOII.AGE  IS  LEAK  IN   CANS. 

I   No.  3  can  marked  "P"  perforated  tin  plate. 

I   No.  3  can  marked  ''O"  seam  leak. 

1   No.  3  can  marked  ''O"  seam  leak. 

I   No.   3  can  marked  *'0'''  seam  leak. 

I   No.  3  can  marked  *T"  seam  leak. 

I   No.  3  can  marked  ''P"  seam  leak. 

I   No.  3  can  marked  ''P"  seam  leak. 

I   No.  2  can  marked  ''P"  seam  leak. 

I   No.  2  can  marked  'T"  cap  leak. 

I   No.  2  can  marked  'T"  seam  leak. 

I   No.  2  can  marked  ^T"  seam  leak. 

I   No.  2  can  marked  ''P"  seam  leak. 

I   No.  2  can  marked  'T"  top  leak. 

I   No.  2  can  marked  'T"  seam  leak. 

I   No.  2  can  marked  *'P"  broken  plate  top  seam. 

I   No.  2  can  marked  ^'P"  seam  leak. 

I   No.  2  can  marked  ''P"  seam  leak. 

I   No.  2  can  marked  ''P"  seam  leak. 

I   No.  2  can  marked  'T"  seam  leak. 

I   gallon  can,  seam  leak. 

Cultures  were  made  of  the  bacteria  found  in  some  of  the  doubt- 
ful cans  and  in  every  case  the  bacteria  were  not  spore-bearing,  but 
belonged  generally  to  the  acetic  acid  varieties.  Pure  cultures  were 
made  of  these  and  a  ten  per  cent  alcohol  solution  was  inoculated 
with  some  of  the  culture,  which  rapidly  attacked  the  alcohol  and 
converted  it  into  acetic  acid.  The  germs  which  were  found  in  these 
cans  are  freely  distributed  in  the  air  and  no  doubt  gained  entrance 
through  the  leaks.  The  time  which  is  given  in  the  letter  for  two 
and  three-pound  tomatoes  is  really  more  than  is  necessary.  Thirty- 
five  to  forty  minutes  for  No.  3  tomatoes  ought  to  sterilize  them 
perfectly.  Toinafoes  need  not  be  exhcmsted.  They  will  keep  all 
right  if  the  process  of  sterilization  is  sufficient.  It  is  customary 
to  add  about  five  minutes'  more  time  for  cold-packed  tomatoes. 
In  order  to  have  the  ends  snap  back  after  sterilization  when  canning 
cold-packed  tomatoes,  it  is  necessary  to  hasten  the  work  after  the 
tomatoes  are  scalded.  The  peeling,  filling  and  capping  must  be 
done  with  great  rapidity  in  order  to  prevent  fermentation  with  the 


412  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

formation  of  even  small  quantities  of  carbonic  acid  gas  which  will 
prevent  the  ends  of  the  cans  from  snapping  back  after  the  process. 
If  there  is  any  delay  between  the  scalding  and  the  processing,  fer- 
mentation will  begin,  particularly  when  the  thermometer  is  in  the 
nineties,  and  of  course  carbonic  acid  gas  is  formed  in  this  fermenta- 
tion. 


Plate  156 

Photomicrograph  of  the  vinegar  bacillus.  Bacillus  Acidi  Aceti,  which  was  iso- 
lated from  a  leaky  can  of  tomatoes.  This  is  one  of  the  lorganisms  which  is 
usually  found  in  the  "mother"  of  vinegar,  which  is  called  Mycoderm  Aceti. 
Solutions  containing  alcohol  in  amounts  less  than  15  per  cent,  are  fermented  and 
the  alcohol  is  converted  into  acetic  acid.  Stained  with  fuchsine  and  photographed 
through   the  microscope.     Magnified  1,200  diameters. 

ANOTHER  CASE  OE  SPOIT.AGK. 

We  investigated  the  cause  of  the  spoilage  of  tomatoes  from 
the  six  cans  expressed  to  the  laboratory.  First  we  examined  these 
cans  carefully  for  leaks  and  found  them  absolutely  well  sealed  and 
no  leaks  in  any  part  of  them.  We  then  sterilized  the  surface  of  the 
tin  by  using  a  Bunsen  flame,  then  with  a  sterile  awl  we  punched 
holes  in  the  cans  and  took  out  some  of  the  tomato  juice  on  a  sterile 
platinum  loop  and  inoculated  dishes  and  tubes  containing  nutrient 
agar,  also  other  tubes  containing  sterile  tomato  juice.  The  cans 
contained  much  gas  and  the  juice  boiled  out  of  them  freely  after 
they  were  punctured.  We  examined  some  of  this  juice  under  the 
microscope  and  found  it  full  of  bacteria,  some  of  them  motile,  others 
having  no  distinct  motion.  We  examined  the  fermented  tomatoes, 
and  found  that  the  seeds  still  retained  the  o-elatinous  substance  which 


CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


413 


Plate  157 

Photomicrograph  of  Bacterium  Prodigiosum,  a  microbe  which  produces  a  beau- 
tiful red  pigment,  which  is  insoluble  in  water,  soluble  in  alcohol  and  ether.  The 
color  is  intensified  by  acids  and  turns  orange-yellow  by  alkalis.  The  bacillus  is 
motile,  having  numerous  long  flagella.  It  produces  methylamin  and  ammonia  and 
sometimes  produces  a  gas  having  the  odor  of  herring  brine.  Produces  formic  acid 
and  carbonic  acid  gas.  It  produces  proteins  of  a  poisonous  nature.  (Lehmann  & 
Neumann.)     Magnified  1,200  diameters. 


Plate  158 


Photomicrograph  of  a  colon-like  bacillus  which  produces  a  light  orange-colored 
pigment  which  is  soluble  in  water.  It  is  an  actively  motile  bacillus  and  has 
numerous  flagella.  We  have  never  before  met  this  species  in  our  work  and  will 
study  its  characteristics  more  thoroughly.  It  is  not  a  spore-bearing  organism 
and  is  easily  destroyed  by  180  degrees  Fahrenheit  moist  heat.  Magnified  1,200 
diameters. 


414  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

is  found  surrounding  the  seeds  in  raw  tomatoes.  This  settled  the 
fact  that  the  tomatoes  had  received  very  Httle  heating.  No  canned 
tomatoes  v^ill  keep  if  the  gelatinous  substance  is  not  cooked  loose 
from  the  seeds.  The  heat  actually  required  to  destroy  the  bacteria 
found  in  tomatoes  will  always  loosen  the  substance  mentioned. 

We  frequently  find  that  the  heat  has  not  been  sufficient  to  de- 
stroy the  life  of  the  seeds,  in  which  case  they  will  grow  if  planted. 
One  of  the  best  ways  of  determining  whether  tomatoes  are  sucffi- 
ciently  processed,  is  to  note  whether  the  gelatinous  substance  has 
been  cooked  loose  from  the  seeds.  Any  process  short  of  accom- 
plishing this  is  insufficient  to  destroy  the  bacteria  associated  with 
the  spoilage  of  tomatoes.  In  order  to  determine  about  what  pro- 
cess these  tomatoes  had  actually  received,  we  began  the  work  of  ob- 
taining pure  cultures  of  the  bacteria  found  in  the  cans.  Four  of  the 
cans  contained  bacteria  which  would  not  grow  in  the  presence  of 
air;  they  were  obligative  anaerobes,  and  it  was  necessary  for  us  to 
grow  them  in  tubes  from  which  the  oxygen  of  the  air  was  entirely 
excluded;  this  we  did  in  the  following  manner:  We  inoculated 
agar  containing  2  per  cent  glucose  solidified  in  the  form  of  slants 
in  test-tubes,  (nearly  all  anaerobic  bacteria  thrive  better  in  media 
containing  glucose),  these  tubes  were  placed  in  larger  tubes  con- 
taining a  mixture  of  pyrogallic  acid  and  sodium  hydroxid,  which 
rapidly  absorbs  the  oxygen  after  the  outer  tube  is  hermetically 
sealed. 

From  two  of  the  cans  we  could  get  pure  cultures  of  aerobic 
bacteria.  One  of  these  was  the  beautiful  red  pigment  bearing  ba- 
cillus prodigiosus,  sometimes  found  on  bread,  rice,  and  other  cereals. 
It  produces  a  beautiful  red  color.  The  other  aerobe  was  also  a 
chromogenic  bacterium  which  produced  a  color  of  light  orange. 
These  two  species  were  actively  motile,  particulary  the  last  men- 
tioned. 

All  of  the  bacteria  isolated  are  species  very  easily  destroyed 
by  heat,  none  of  them  being  able  to  withstand  210  degrees  Fahr.. 
and  the  conclusion  we  reached  was,  that  these  cans  had  not  been 
processed  long  enough  for  even  180  degrees  of  heat  to  reach  the 
center  of  the  contents.  Just  what  the  conditions  were,  we  cannot 
say,  since  we  were  not  present,  but  there  cannot  be  any  question 
of  the  correctness  of  our  conclusions  because  the  bacteria  present 
in  the  tomatoes  will  perish  at  180  degrees  Fahr.,  and  the  natural 
condition  of  the  seeds  is  evidence  that  no  high  temperature  ever 
reached  the  center  of  the  can. 

It  is  necessary  in  using  any  processing  system,  to  see  that  the 
goods  are  subjected  to  the  required  temperature  for  the  time  nec- 
essary to  accomplish  sterilization,  and  the  accomplishment  of  this 


TOMATOES.  415 

end  is  under  control  of  the  operator,  whether  working  with  the  or- 
dinary cooking  vats  or  kettles,  or  with  a  continuous  conveying  sys- 
tem. 


SWELLED  TOMATOES. 

We  have  received  several  samples  of  swelled  tomatoes,  the 
cause  of  which  we  find  is  due  to  leaky  cans.  The  following  is  a 
sample : 

When  the  samples  of  swelled  tomatoes  reached  us  several  cans 
were  burst  in  the  seams  and  the  contents  were  gone.  We  took  a 
can  which  had  no  apparent  leak  and  after  incubating  it  examined  the 
juice  and  found  two  species  of  bacteria  present.  One  was  the 
acetic  acid  bacterium  and  the  other  was  a  very  actively  motile  bacil- 
lus which  we  were  able  to  cultivate  in  pure  cuiture  only  on  tomato 
agar  at  first.  We  could  not  get  a  growth  on  the  regular  beef  juice 
agar  at  first,  but  after  two  subcultures  we  were  able  to  get  a  fine 
growth.  This  is  a  remarkable  peculiarity  of  some  bacteria,  they 
become  accustomed  to  a  certain  kind  of  food  and  do  not  readily 
thrive  when  streaked  on  a  new  substance.  This  is  a  well  known 
characteristic  of  many  pathogenic  organisms;  they  will  grow  quite 
well  in  the  body,  but  when  planted  on  artificial  media  they  grow  but 
scantily  at  first,  but  after  several  subcultures  they  multiply  very 
readily  and  to  some  extent  lose  some  of  their  pathogenic  character- 
istics and  become  saphrophytic.  Another  peculiarity  of  this  to- 
mato bacillus  was,  after  we  had  made  several  subcultures,  we  were 
unable  to  get  a  good  growth  on  tomato  juice  again,  but  on  tomato 
juice  which  had  fermented  it  grew  quite  well.  This  would  indicate 
that  it  had  nothing  to  do  with  the  first  fermentation,  but  found  a 
suitable  substance  after  that  fermentation  on  which  it  could  thrive 
luxuriantly. 

Microscopical  appearance.  Large,  straight  rods  three  to  six 
times  as  long  as  broad,  with  square  ends,  and  forms  chains  com- 
posed of  several  cells.  The  rods  are  beautifully  flagellated,  having 
many  of  these  organs  of  locomotion  attached  to  the  entire  surface. 
The  bacillus  looks  something  like  bacillus  megatherium,  but  dif- 
fers from  it  in  several  points,  its  active  motility,  the  rods  are  not 
bent,  the  ends  are  square,  and  it  has  more  flagella. 

The  spores  of  this  bacillus  are  small  and  centrally  located  in 
the  rods,  they  are  very  resistant  to  heat,  and  could  not  be  destroyed 
by  the  temperatures  usually  given  tomatoes  for  sterilization.  As 
we  have  said,  however,  it  will  not  thrive  readily  on  unfermented  to- 
matoes, consequently  we  are  not  usually  troubled  with  it,  unless  we 
permit  the  peeled  tomatoes  to  stand  too  long  before  they  are  pro- 
cessed, or  until  fermentation  has  started. 


416 


CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


Plate  159 

Photomicrograph  of  a  tomato  bacillus  greatly  resembling  megatherium  in  size 
and  some  other  characteristics,  but  is  straight  and  has  square  ends.  Gives  rise 
to  foul  odor  in  tomatoes.  It  is  actively  motile  owing  to  its  numerous  flagella, 
which  were  demonstrated  by  our  own  special  method  from  a  very  young  agar 
culture.  This  bacillus  has  many  peculiarities  as  to  its  food  requirements.  (See 
text.)  It  forms  spores  and  is  present  in  tomatoes  only  after  a  previous  fermen- 
tation.    Magnified  1,200  diameters. 


Plate  160 


Photomicrograph  of  spores  and  rods  of  bacillus  shown  in  Plate  159.  Owing 
to  the  slime  formed  in  the  old  culture,  it  was  difficult  to  get  a  good  slide  prepara- 
tion of  the  spores.  The  spores  are  quite  small  in  proportion  to  the  size  of  the 
rods.     Stained  with   fuchsine.     Magnified   l.COD   diameters. 


TOMATOES.  41t 

For  a  time  we  were  unable  to  determine  just  why  this  organ- 
ism was  present  in  the  can  examined,  but  we  finally  came  to  the 
conclusion  that  there  must  be  a  leak  in  the  can  somewhere,  so  we 
soldered  up  the  hole,  then  we  attached  a  check  valve  and  pumped 
about  25  pounds  of  air  into  the  empty  can.  We  then  placed  the 
can  under  water  and  there  were  several  fine  streams  of  air  bubbles 
which  came  from  the  leaks,  which  were  invisible  to  the  eye. 


418  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

CHAPTER  XIV. 

Corn 

A  Short  Historical  Sketch.  The  Canning  of  Corn.  Suggestions 
for  Canning  and  Processing.  Cause  of  Sour  Corn.  Laboratory 
Work  on  Spoilage  Cases.  Spoilage  J^ue  to  Poor  Tin  Plate. 
Spoilage  Due  to  Imperfect  Circulation  in  the  Process.  Bacteria 
Which  Cause  Souring  of  Corn.  Insufhcient  Sterilization  and 
Its  Results.  Discoloration  of  Corn  Due  to  Products  Elaborated 
by  Bacteria;  Other  Causes.  Method  of  Separating  Sour  Corn 
From  Good.  Method  of  Determining  Cause  of  Spoilage, 
Whether  Leaks  or  Insufficient  Sterilization. 


The  history  of  corn  packing  dates  back  to  the  year  1839, 
when  Isaac  Winslow  began  his  experiments.  Our  readers  are  re- 
ferred to  the  historical  sketch  by  Mr.  F.  O.  Conant,  of  Portland, 
Me.,  in  ''Science  and  Experiment  as  Applied  to  Canning,"  p.  13. 

Probably  nothing  in  the  canning  line  has  given  the  canners 
more  trouble  than  corn.  It  seems  that  it  is  liable  to  be  invaded  at 
times  by  extremely  resistant  forms  of  bacteria.  In  the  early  his- 
tory of  corn-packing,  W^inslow  was  able  to  sterilize  his  cans  by 
simply  boiling  them  in  water  for  several  hours.  The  history  of 
his  successes  and  failures,  and  not  only  his,  but  also  his  contem- 
poraries, makes  interesting  reading.  When  the  boiling  temperature 
ceased  to  be  effective,  the  cans  were  subjected  to  235-240°  for  an 
hour  or  more,  and  this  temperature  seemed  to  give  good  satisfac- 
tion for  a  long  time.  It  subsequently  failed,  however,  and  the 
canners  had  complaints  of  the  corn  turning  sour. 

Among  the  first  investigators  to  study  this  problem  along  sci- 
entific lines  were  Mr.  Prescott  and  Mr.  Underwood,  of  the  Biologi- 
cal Department  of  the  Boston  School  of  Technology.  At  a  meeting 
of  the  Atlantic  State  Packers'  Association  held  at  Buffalo  in  F^ebru- 
ary,  189S,  these  two  gentlemen  made  known  the  results  of  their 
investigations.  These  papers  were  full  of  interesting  and  valuable 
information. 

A  great  deal  of  the  souring  of  corn  results  from  two  different 
processes,  one  where  the  souring  had  been  accomplished  prior  to 
sterilization  and  the  other  where  the  same  phenomenon  was  noticed 
in  the  cans  after  sterilization,  and  this  was  due  to  living  organisms 
which  had  not  been  killed  in  the  process.  Strange  to  say,  the  de- 
composition took  place  without  the  evolution   of  any  gas.     The 


CORN.  419 

sugar  in  the  corn  was  converted  into  lactic  acid,  in  some  cases, 
butyric  acid  and  valeric  acid,  and  there  was  formed  sulphuretted 
hydrogen  in  various  amounts.  It  was  found  necessary  to  increase 
the  process  of  corn  up  to  250^  F.  for  sixty-five  minutes.  In  some 
cases  even  this  temperature  has  proved  ineffective,  but  if  the  con- 
sistency is  correct  this  heat  will  kill  all  spores. 

As  a  general  proposition,  then,  we  can  say  that  ^50°  for  sixty- 
five  minutes  is  a  safe  process  for  corn  if  it  is  not  too  dry.  There 
must  be  enough  fluid  to  carry  the  temperature  from  the  parts  near- 
est the  tin  to  the  center.  If  there  is  not  enough  fluid  to  do  this, 
an  impenetrable  wall  will  form  within  the  can,  and  the  spores  (in 
the  center  of  the  cans)  will  not  be  subjected  to  the  temperature 
which  registers  on  the  retort,  and  consequently  may  live  through 
any  process. 

Some  canners  are  reported  as  being  in  the  habit  of  using  sul- 
phites for  bleaching  purposes.  This  practice  is  extremely  danger- 
ous for  several  reasons.  First,  sulphites  will  attack  the  tin  plate  of 
poor  quality  and  cause  dark  discoloration  in  the  corn.  Second, 
such  corn  has  a  sickly,  unnatural  appearance.  Third,  state  food 
chemists  are  liable  to  condemn  such  goods  as  illegal,  and  thus  bring 
discredit  upon  the  whole  industry.  It  is  reported  that  some  pack- 
ers have  been  using  saccharin  for  sweeting  purposes  instead  of  cane 
sugar.  Saccharin  has  been  declared  injurious  by  some  authorities,, 
although  I  have  never  heard  of  any  experiments  being  made  to 
determine  the  truth  of  the  statement.  A  favorite  argument  of 
food  experts  is  that  saccharin  is  a  fraud,  it  is  used  as  a  substitute 
for  cane  sugar,  and  therefore  is  an  adulterant  in  the  eyes  of  the 
law.  We  cannot  enter  into  argument,  but  it  might  be  well  to  cease 
using  saccharin  until  some  definite  understanding  is  reached  on  this 
point. 

Corn,  when  it  is  delivered  at  the  factory,  should  be  worked  up 
as  rapidly  as  possible.  It  is  the  custom  in  some  houses  to  pack 
two  grades — a  first  and  a  second  grade.  Frequently,  the  whole 
first  grade  is  run  through  while  the  corn  intended  for  the  second 
grade  is  piled  up  in  great  heaps.  These  heaps  may  remain  long 
enough  to  have  lactic  decomposition  set  in,  and  sour  corn  will  surely 
result,  because  the  lactic  acid  formed  in  the  corn  can  never  be  cooked 
out  again  by  any  sterilizing  process.  Corn,  when  delivered  at  the 
factory,  contains  a  large  number  of  spore-bearing  bacteria  of  vari- 
ous kinds  on  the  husks,  on  the  silk  and  between  the  kernels  of  corn. 
When  the  corn  is  husked  and  run  through  the  corn  cutter  these 
spores  are  thoroughly  mixed  in  with  the  corn.  The  corn  goes 
through  the  silking  machines  and  then  into  the  cooker  and  all  of 
the  fully  developed  bacilli  are  destroyed  by  the  cooking,  but  the 
spores  are  not — they  go  into  the  cans  and  into  the  final  process,  and 


420  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

that  process  must  be  about  250°  for  sixty-five  minutes  in  order 
to  insure  perfect  sterilization. 

The  calcium  system  offers  some  improvement  over  the  retort 
for  sterilization  because  the  cans  are  somewhat  agitated  whiJe  going 
through  the  bath.  This  system  is  cheaper  than  any  other  and  is 
attended  with  less  steam  and  general  inconvenience  than  the  regular 
retort.  In  the  following  pages  we  will  give  some  actual  laboratory 
work  done  on  spoiled  corn  and  the  results  obtained,  and  this  will  be 
valuable  to  the  canner. 

The  following  is  an  extract  of  an  address  delivered  before  the 
canners  at  Columbus,  O.,  in  February,  1905. 

Of  all  canned  goods,  corn  seems  to  have  given  the  packer  more 
trouble  than  anything  else — there  were  eighteen  separate  investiga- 
tions of  spoiled  corn — and  it  will,  no  doubt,  be  interesting  for  us 
to  draw  some  conclusion  from  the  experience  we  have  had  with  so 
many  different  cases  of  spoilage. 

If  you  will  remember,  last  year  I  stated  that  in  nine  cases  out 
of  ten  the 

CAUSE  OF  SOUR  CORN 

was  due  to  the  souring  of  the  raw  material  before  it  was  canned. 
While  this  statement  was  true  at  that  time,  it  is  not  true  today. 
The  majority  of  the  cans  of  spoiled  corn  investigated  during  this 
year  at  the  laboratory,  were  sour  on  account  of  incomplete  steriliza- 
tion. There  were  two  or  three  cases  only  of  sour  corn  which  had 
soured  previous  to  the  sterilizing  process.  Let  us  state  the  nature 
of  this  spoilage :  In  the  first  place  we  find  that  there  are  two  dis- 
tinct forms  of  spoilage  due  to  insufficient  sterilization. 

In  one,  the  can  swells  and  the  contents  become  putrid,  the  pres- 
sure of  gas  sometimes  exceeding  35  to  40  pounds,  to  the  square 
inch.  We  made  a  very  interesting  experiment  to  determine  the 
pressure  necessary  to  burst  a  certain  make  of  cans,  as  follows :  We 
attached  the  can  to  a  steam  autoclav,  or  steam  retort,  and  raised 
the  pressure  gradually  up  to  30  pounds  without  bursting  the  can. 
We  were  afraid  to  raise  it  any  higher  for  fear  of  some  accident,  but 
we  are  satisfied  that  it  would  have  required  at  least  35  to  40  pounds* 
pressure  to  burst  the  can. 

The  bursting  of  the  cans  is  quite  a  common  phenomenon  seen 
in  piles  of  corn,  so  that  the  pressure  produced  by  the  bacteria,  which 
are  responsible  for  the  process  of  decomposition,  is  probably  more 
than  35  or  40  pounds.  Bacteria,  which  produce  gas  in  canned  corn, 
are  generally,  although  not  always,  anaerobic ;  that  is,  they  will  not 
grow  in  the  presence  of  air.  Most  of  this  species  are  common  in 
the  soil  and  in  decomposing  organic  matter.  There  is  another  class 
of  germs  which  produce  gas  and  cause  the  spoilage  of  corn ;  these 


CORN.  421 

are  aerobic;  that  is,  they  are  able  to  grow  in  the  presence  of  oxy- 
gen.    Both  of  these  varieties  produce  spores  of  great  vitality. 

The  other  form  of  spoilage  is  a  souring  of  the  contents  of  the 
can  without  any  outward  appearance  of  the  trouble  within.  Some- 
times these  goods  when  opened  taste  remarkably  well  on  the  surface, 
but  in  the  center  they  are  putrid  and  the  odor  is  abominable.  This 
class  of  germs  is  generally  aerobic,  and  the  spores  are  probably  more 
resistant  to  high  temperatures  than  the  gas  producers. 

These  bacteria  certainly  give  the  canner  considerable  trouble, 
because  the  cans  do  not  swell,  and  it  is  a  very  tedious  and  trouble- 
some matter  to  pick  out  those  cans  which  are  good  and  those  which 
are  bad. 

The  following  test  gave  excellent  results  in  one  case  where  it 
was  carried  out  carefully:  The  cold  cans  of  corn  are  put  in  the 
steam  retort  and  the  temperature  was  raised  to  240  degrees,  and 
maintained  so  for  65  minutes.  They  were  then  taken  out  of  the 
retorts  as  soon  as  the  pressure  ran  down,  and  put  into  cold  water  for 
five  minutes.  They  were  then  piled  out  in  rows  so  that  both  ends 
were  visible.  After  three  or  four  hours  many  of  the  ends  were 
drawn  in ;  these  were  sorted  out  and  heated  for  about  seven  minutes 
at  150  degrees — all  cans  which  did  not  swell  in  this  temperature 
were  good.  Any  which  showed  slight  swelling  were  somewhat 
affected.  Some  of  the  cans  were  swelled  on  one  end,  while  the  other 
end  had  drawn  in ;  some  of  these  wdien  again  heated  did  not  swell, 
and  were  good.  All  cans  wdiicli  do  not  swell  in  this  second  heating 
can  be  marketed  as  first-class  goods.  The  balance  are  affected  more 
or  less  and  are  probably  a  total  loss. 

I  will  explain  the  cause  of  this  peculiar  phenomenon.  The 
bacteria  which  cause  the  souring  and  putrefaction  of  canned  corn 
without  swelling  cans  produce  a  substance  called  sulphuretted  hy- 
drogen. This  is  a  gas  which  is  taken  up  by  liquids  and  does  not 
affect  the  vacuum  until  it  has  saturated  the  liquid,  when  the  surplus 
will  cause  the  swelling  of  the  can.  It  rarely  happens,  however, 
that  it  will  be  formed  in  sufficient  quantities  to  cause  the  swelling, 
and  as  fast  as  it  is  generated  it  is  usually  absorbed  by  the  fluid. 
When  the  cans  are  put  into  a  retort  and  the  temperature  brought  up 
to  250  degrees  for  65  minutes  the  heat  expands  the  gas  and  it  is  lib- 
erated from  the  fluid  so  that  it  will  force  both  ends  out  and  will  not 
be  absorbed  again  by  the  liquid  until  it  has  become  quite  cold. 
Usually  there  is  enough  gas  left  unabsorbed  to  destroy  the  vacuum 
and  this  will  leave  the  ends  puffed  out  somewhat  even  after  cooling. 

Nearly  every  packer  who  has  experienced  losses  of  this  kind 
has  noticed  that  a  large  number  of  cans  are  not  thus  affected.  These 
good  cans  are  scattered  throughout  the  pile  in  various  percentages. 
Now,  the  question  comes  up,  why  is  it  that  a  certain  proportion  will 


422  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

Spoil  while  the  balance  will  be  good?  Why  is  it  that  the  process 
was  sufficient  in  one  case  to  destroy  the  resistant  forms  of  bacteria 
and  was  not  sufficient  in  the  other  case?  All  the  cans  were  run 
through  the  same  process  and  were  treated  apparently  in  the  same 
manner  all  through  the  various  processes  of  manufacture,  and  yet 
some  of  them  will  spoil  and  some  of  them  will  be  good. 

Whenever  spoilage  occurs  in  any  kind  of  goods  this  phenom- 
enon is  generally  noticed,  and  the  reason  for  this  may  be  thus  ex- 
plained :     It  is  generally  due  to  variation  in  the  consistency. 

A  careful  study  was  made  of  the  consistency  of  different  cans 
of  corn  in  the  various  cases  of  spoilage  investigated.  Where  the 
corn  was  quite  dry  and  very  little  juice  was  present,  bacteria  seemed 
not  to  have  been  destroyed.  Corn  is  not  easily  penetrated  by  heat. 
The  kernels  which  lie  next  to  the  tin  are  heated  very  soon  after 
the  proper  temperature  is  registered  on  the  retort  thermometer; 
probably  the  kernels  next  to  them  are  heated  sufficiently;  then  we 
can  imagine  a  sort  of  impenetrable  wall  of  corn  all  around  the  can 
which  takes  up  nearly  all  the  heat  and  prevents  it  from  penetrating 
to  the  center  of  the  can.  In  the  center  of  the  can  are  numbers  of 
spores;  these  spores  gain  entrance  to  the  corn  in  the  mixer  and 
cooker ;  they  are  not  destroyed  in  the  cooker-  and  pass  through  the 
filling  machines  into  the  cans  without  being  harmed  in  the  least. 
These  spores  in  the  center  of  the  can,  surrounded  and  protected  as 
they  are  by  an  impenetrable  wall  of  corn,  withstand  temperatures 
registered  on  the  retort  thermometer  which  would  otherwise  be  suf- 
ficient to  destroy  all  life.  If  there  were  just  a  sufficient  amount  of 
juice  to  flow  in  between  the  grains  of  corn  and  penetrate  to  the 
center,  this  juice  would  carry  the  heat  necessary  to  destroy  spore 
life;  250  degrees  Fahrenheit  for  ten  to  fifteen  minutes  will  abso- 
lutely destroy  the  most  resistant  spores  known,  and  all  that  is  re- 
quired is  to  add  to  this  time  the  number  of  minutes  necessary  for 
that  temperature  to  register  at  the  center  of  the  can.  I  would  make 
the  suggestion,  therefore,  that  the  canners  adopt  a  rule  of  adding  a 
certain  quantity  of  brine  to  each  can  in  order  to  insure  sufficient 
moisture  to  carry  the  heat  to  all  parts  of  the  can. 

USE  01-'  STARCH  DANGEROUS. 

There  may  be  some  packers  who  use  a  little  starch  in  order  to 
give  the  corn  a  creamy  consistency.  In  the  light  of  what  we  have 
said,  this  practice  may  be  considered  dangerous,  because  starch  will 
interfere  with  the  fluidity.  Nearly  every  packer  knows  the  result 
of  delays  prior  to  sterilization.  Sour  corn  results  from  piling  the 
husked  corn  in  heaps,  where  it  becomes  heated.  There  were  only 
two  cases  of  sour  corn  from  delays  of  this  kind,  and  we  take  it  for 
granted  that  the  packers  have  become  familiar  with  the  dangers  of 
unnecessary  delays  before  sterilization. 


CORN.  .  423 

some  ivaboratory  work  on  corn. 

souring  of  corn. 

National  Cannkrs'  Laboratory, 
Aspinwall,  Pa. 

Gknti^kmkn  : — We  are  making  you  an  express  shipment  pre- 
paid today  of  i  dozen  cans  corn,  on  the  bottoms  of  which  some  are 
marked  ''G"  for  good,  and  some  ''S"  for  sour. 

We  wish  you  to  make  an  examination  of  these  goods  and  let 
us  have  your  report  as  to  what  you  hnd.  All  these  goods  were 
processed  exactly  the  same,  viz. :  63  minutes  at  250  degrees  F.,  with 
hot  water  and  steam  combined,  and  we  would  like  to  know  why  it 
is  in  the  condition  it  is. 

When  the  samples  of  sour  corn  arrived  we  made  culture  pre- 
parations, and  inoculated  them  with  the  juice  from  each  can,  taken 
under  aseptic  precautions.     The  culture  dishes  showed  no  growth 


Plate  161 

Defective  tin   from   can  of   corn.     Photomicrograph   of   outside   surface   showing 
three  holes  near  the  center.     Magnified  200  diameters. 

of  bacteria,  except  from  two  cans ;  the  balance  were  incubated  at 
98°  F.,  until  the  agar  dried  up,  but  no  colonies  made  their  appear- 
ance. From  two  cans,  however,  we  obtained  a  number  of  colonies 
and  upon  examination  we  found  that  some  of  these  were  micrococci, 
and  ordinary  lactic  acid  bacteria,  which  could  not  possibly  withstand 
any  sterilization  commonly  given  canned  corn.  Even  boiling  tem- 
perature destroys  these  bacteria.  Our  idea  was  at  first  that  the  cul- 
tures were  contaminations  from  the  air,  and  we  discarded  these  and 
prepared  another  set  of  dishes  and  obtained  similar  results.     We 


424  CANNING  x\ND  PRESERVING  OF  FOOD  PRODUCTS. 

therefore  concluded  that  we  must  have  exposed  the  juice  to  the  air 
and  reasoned  that  the  cans  were  contaminated  by  some  carelessness 
or  oversight  in  our  manipulations.  We  therefore  opened  all  the 
cans  and  examined  the  contents.  All  were  swxet  and  good  except- 
ing the  tw^o  cans  from  which  we  had  obtained  cultures.  The  juice 
in  these  cans  seemed  to  have  a  watery  and  curdled  appearance,  the 
thin  fluid  presenting  a  faintly  bluish  cast  by  diffused  light.  We  ex- 
amined the  soldering  of  these  cans  critically,  looking  for  pin  hole 
leaks,  but  none  were  found,  so  we  began  the  search  over  the  sur- 
face of  the  tin  for  imperfections  and  perforations.  On  the  outside 
of  the  cans  there  were  numerous  rust  spots  having  dark  centers, 
and  we  found  various  places  where  the  tin  was  perforated  with  ex- 
ceedingly small  holes.     The  photomicrographs  show  three  holes, 


Plate  162 

Defective  tin  from   same   can   as   plate   161   Photomicrograph    of   inside    surface 
directly  opposite  of  plate  1,  showing  same  three  holes.     Magnified  200  diameters. 

one  was  taken  from  the  inside  surface  and  the  other  from  the  out- 
side surface  directly  opposite  from  each  other,  under  a  magnification 
of  200  diameters. 

This  discovery,  of  course,  cleared  up  the  mysterious  appear- 
ance of  the  non-sporulating  varieties  of  bacteria  which  made  their 
appearance  in  the  Petri  dishes.  Not  satisfied  with  this  investiga- 
tion, we  notified  the  packers  to  forward  another  lot  of  cans,  and 
upon  receipt  of  these  we  prepared  a  large  number  (about  30)  of 
Petri  dishes,  using  as  a  medium  for  cultivating  the  bacteria,  pure 
sweet  corn  juice  containing  ij^  per  cent  agar,  marking  each  dish 
with  the  number  indicated  on  the  can  from  which  it  was  taken. 
After  twenty-four  hours  the  dishes  from  several  cans  contained 
very  small  colonies,  and  after  several  hours  more  we  were  able  to 
isolate  the  bacteria. 


CORN. 


425 


%^ 


r 


/;# 


Plate  163.     Bacillus  Mesentericus  Fuscus 

Photomicrograph  showing  bacilli  endowed  with  numerous  flagella.  This  or- 
ganism was  isolated  from  a  can  of  sour  corn.  It  produces  no  gas  and  gives 
rise  to  spores  of  great  vitality.     Magnified  1,500  diameters. 


"^K 


«»  % 


%      ^ 


«»  #  ^ 


/ 


1^     (# 


\i|i^  ^ 


%  i»       t 


Plate  164,     Bacillus  Mesentericus  Fuscus,  showing  Spores 
Magnified   1,500   diameters. 


426  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

One  colony,  first  examined,  was  perfectly  round,  evenly  bord- 
ered, very  dark  in  the  center,  shaded  down  to  a  yellow  near  the  edge, 
under  a  magnification  of  60  diameters  by  transmitted  light. 

The  natural  size  was  about  one  millimeter  in  diameter,  and  had 
a  lustrous  bluish  cast  with  a  dark  spot  in  the  center.  This  proved 
to  be  the  lactic  acid  bacillus  and  numerous  similar  colonies  after- 
wards made  their  appearance.  We  have  shown  the  illustration 
(of  lactic  acid  bacteria)  see  Plate  39.  This  was  from  a  perforated 
can. 

Another  colony  was  examined  which  resembled  the  above  very 
closely  except  that  it  had  a  crumby  appearance.  It  looked  as  if  it 
had  broken  glass  or  sand  sprinkled  over  the  surface.  We  made  a 
streak  culture  of  this  organism  and  found  that  it  was  a  motile  spore 
bearing  bacillus,  which  produced  no  gas.  It  grew  rapidly  over  the 
surface  and  seemed  to  grow  downward  into  the  agar  as  well  as 
over  the  surface,  the  center  of  the  growth  being  covered  with  small 
wrinkled  folds,  while  the  extending  layer  was  very  thin  and  almost 
transparent.  The  organism  grew  Avell  both  as  an  aerobe  and  as  an 
anaerobe,  but  in  the  last  named  condition  seemed  to  produce  more 
acid,  which  was  something  like  phosphoric  acid,  very  sour.  The 
growth  on  corn  juice  was  rapid  with  no  gas,  and  the  juice  seemed 
to  present  the  same  curdled  appearance  noticed  on  opening  the  cans 
of  sour  corn. 

The  rods  begin  to  form  spores  after  the  second  day.  and  when 
examined  in  the  living  state  a  degeneration  of  the  cell  may  be  ob- 
served, the  protoplasm  becoming  less  homogeneous,  and  sporangic 
granules  are  seen  as  is  the  case  during  plasmolysis.  After  a  time 
the  granules  seem  to  collect  and  a  bright  shining  spot  appears  near 
one  end  of  the  rod,  and  this  spot  seems  to  take  on  a  definite  shape ; 
it  is  the  spore  forming  within  the  cell.  Our  photomicrograph 
shows  some  of  these  rods  which  have  the  spores  within.  There  are 
a  number  of  rods  which  are  barren,  that  is  to  say,  they  will  not  pro- 
duce spores;  such  rods  are  met  with  in  nearly  all  cultures.  The 
membranes  of  these  spores  are  quite  thick  and  are  able  therefore 
to  withstand  high  temperatures,  or  other  unfavorable  conditions, 
and  afterwards  develop  into  vegetating  rods  when  conditions  of  en- 
vironment are  favorable.  In  order  to  give  the  packers  some  idea 
of  the  size  of  such  spores,  it  would  take  about  25,000  of  them 
placed  side  by  side  to  measure  one  inch ;  it  would  take  200  of  them, 
placed  end  to  end,  to  reach  across  a  hair.  An  ordinary  pin  hole  leak 
in  a  tin  can  is  large  enough  to  admit  50.000  of  these  spores  at  one 
time  if  that  many  could  be  collected  and  crowded  together.  The 
photomicrographs  of  the  various  species  are  magnified  from  1,000 
to  1,500  diameters,  which  is  a  real  magnification  of  from  one  to 
two  and  a  half  million  times,  so  that  our  readers  can  appreciate  the 


CORN.  427 

•extreme  delicacy  of  the  photographers's  work,  which  must  be  done 
through  the  microscope,  everything  being  absokitely  quiet  and  the 
brightest  radiant  possible.  The  can  from  which  bacillus  Mesenteri- 
cus  Fuscus  was  taken  was  not  a  leak,  but  the  sterilization  was  in- 
complete. 

In  another  can  of  sour  corn  we  found  another  kind  of  organism 
associated  with  the  bacillus  just  described.  We  designated  this  as 
bacillus  Ij'odermos. 

After  twenty-four  hours,  fine  water  points  appeared  on  the 
surface  of  the  culture  medium,  and  as  they  grew  older  these  colonies 
took  on  a  reddish  yellow  color  at  a  magnification  of  60  diameters  by 


Plate  165.     Bacillus  Liodermos 

Photomicrograph  of  bacilli  showing  their  numerous  flagella  which  are  some- 
what matted  together.  Vegetating  rods  obtained  from  a  culture  on  Agar  incu- 
bated at  98  degrees  Fahrenheit  for  eight  hours.  Flagella  stained  by  our  own 
method.  This  organism  was  isolated  from  a  can  of  sour  corn.  It  produces  no 
gas,   forms  butyric  acid  and  H2  S.    Magnified  1,500  diameters. 

transmitted  light.  Naturally  the  colonies  are  about  2  m.  m.  in  diam- 
eter and  round,  somewhat  elevated,  but  when  magnified  slight 
growths  can  be  seen  extending  outward  from  tlie  peripheiy.  The 
agar  streak  culture  is  a  moistly  shining,  dirty  layer,  with  a  thin, 
punctuated,  transparent  growth  pushing  ahead  of  the  older  streak. 
This  layer  rapidly  extends  to  the  walls  of  the  dish  even  up  the  sides 
for  a  short  distance.  The  bacilli  are  about  3  to  6  />t  long, 
having  numerous  hair- like  organs  of  locomotion.   They  form  chains 


428  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

and  have  a  tendency  to  collect  in  bunches,  being  matted  together, 
held,  no  doubt,  by  interlaced  flagella.  Our  photomicrograph  shows 
them  thus  connected.  This  bacillus  produces  butyric  acid  and  sul- 
phuretted hydrogen,  but  no  gas.  When  we  tasted  the  juice  of  this 
can  it  was  somewhat  disagreeable,  having  not  only  a  sour  taste  but 
a  flavor  not  at  all  pleasant. 

This  bacillus  forms  spores  which  are  located  at  the  center  of  the 
rods,  and  are  extremely  resistant  to  high  temperature.  We  have 
reserved  a  culture  of  them  in  the  laboratory  for  further  study. 

One  can  contained,  with  others,  a  bacillus  which  produced  a 
bitter  principle  not  unlike  that  of  raw  peas.     The  juice  of  this  can 


-%1  I  ^  J' 


%^ 


Plate  166.      Bacillus  Liodernios 

Photomicrograph  showing  rods  containing  median  spores,  tarren  rod  and  free 
spores.  This  preparation  was  made  from  a  culture  on  Agar  four  days  old.  and 
stained  with  carbol  fuchsine.  These  spores  are  the  seed  forms  of  the  bacilli 
shown  in  Plate  165.  They  are  very  resistant  to  heat,  being  able  to  withstand 
boiling  for  several  hours.     Magnified  1,500  diameters. 

was  different  in  flavor  from  any  of  the  others.  This  was  marked 
Can  No.  i,  and  when  the  colonies  began  to  grow  we  noted  other 
varieties  previously  examined,  also  this  one,  which  is  designated  as 
Bacillus  Bittergenus. 

The  colonies  were  all  deeply  imbedded  in  the  agar,  none  at  all 
appearing  on  the  surface,  which  indicates  that  it  favors  an  anaerobic 
condition.  The  streak  also  had  a  tendency  to  grow  downward  into 
the  medium.  The  deep  colonies  were  opaque,  granular  and  brown. 
When  planted  in  sweet  corn  juice  a  bitter  flavor  was  imparted.  The 
spores  are  medium. 


CORN. 


429 


Plate  167 

Photomicrograph  of  Bacillus  Bittergenus,  a  very  actively  motile  bacillus  iso- 
lated from  a  can  of  bitter,  sour  corn.  It  has  numerous  flagella  and  stains  well 
by  our  laboratory  method.  It  is  an  anaerobe  facultative  aerobe  and  imparts  a 
slightly  bitter   flavor   to   corn.     Magnified   1,500  diameters. 


;tn,** 


- 1  :tf^ 


w 


Plate  168 

Photomicrograph  of  the  spore  forms  of  Bacillus  Bittergenus.  The  spores  are 
median  and  quite  large  in  comparison  with  the  breadth  of  the  rods.  This  speci- 
men was  stained  with  carbol  fuchsine  from  an  Agar  culture  and  tested  for  vital- 
ity.    It  resists  boiling  for  hours.     Magnified  1,500  diameters. 

The  sample  of  salt  proved  to  be  as  good  as  any  ordinary  table 
salt,  and  showed  no  acid  reaction,  being  neutral. 

The  sugar  crystals  proved  to  be  saccharin,  giving  the  violet  re- 
action by  the  ferric  chlorid  test,  after  being  converted  into  salicylic 
acid. 


430  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

CONCI.USIONS. 

The  cans  used  for  this  lot  of  corn  had  a  very  inferior  coating' 
of  tin,  and  we  would  recommend  a  better  quality  of  tin  plate  for 
packing  corn. 

The  process  of  250°  F.  for  63  minutes  would  seem  to  be  suf- 
ficient if  the  circulation  were  all  right.  We  do  not  regard  a  steam 
and  w^ater  process  as  reliable  as  dry  steam,  for  the  reason  that  water 
has  not  as  good  circulation  as  dry  steam.  The  same  process  with 
dry  steam  and  free  exhaust  will  undoubtedly  sterilize  the  corn  per- 
fectly. 

This  process  will  discolor  corn  slightly  unless  the  cans  are 
chilled  wnth  cold  water.  Our  experience  has  been  that  the  best  way 
to  accomplish  this  is  to  run  cold  water  into  the  retorts  through  the 
lid  before  opening  them,  wdien  the  temperature  falls  to  about  220^ 
F. 

We  would  recommend  that  the  use  of  saccharin  be  discon- 
tinued, because  it  is  illegal  in  many  states,  and  canned  goods  or  any 
other  food  containing  this  sweetener,  are  liable  to  be  analyzed  and 
condemned  by  the  authorities. 

Mr.  E.  W.  DuckwalIv, 
Aspinwall,  Pa. 

Dear  Sir  : — We  have  been  surprised  to  learn  that  some  of  our 
corn  has  turned  sour.  Only  one  or  two  cans  in  a  case  have  been 
discovered  so  far  and  they  are  among  the  solid  pack  of  1903.  We 
are  sending  you  by  express  prepaid  several  cans  which  may  be  sour. 
We  would  like  to  have  you  make  a  bacteriological  examination  of 
these,  and  would  be  pleased  to  hear  the  results.  We  have  been  pro- 
cessing at  245°  F.  for  sixty-five  minutes,  but  this  is  probably  too 
low.  Would  you  advise  us  to  increase  it  to  250°  F.,  as  you  sug- 
gest in  your  writings?     Awaiting  your  reply,  we  remain, 

Yours  very  truly, 


Only  two  cans  were  found  to  be  sour  in  the  case  of  goods  re-- 
ceived,  and  we  made  plate  cultures  of  the  juice  by  streaking  a 
number  of  Petri  dishes  containing  nutrient  corn  juice  agar.  With- 
in thirty-six  hours  we  had  a  number  of  colonies,  many  of  which 
were  the  same.  We  found  only  two  colonies  which  showed  any 
marked  difference.  These  we  transplanted  into  bouillon,  and  pelli- 
cles formed  rapidly  on  the  surface,  one  being  much  more  wrinkled 
than  the  other,  growing  fast  to  the  walls  of  the  tube,  and  not  easily 
precipitated  by  shaking. 


CORN. 


431 


From  the  bouillon  culture  -we  streaked  new  culture  plates,  and 
obtained  a  rapidly  spreading  growth  in  eight  hours,  which  was 
composed  of  very  motile  bacteria.  From  this  growth  we  obtained 
a  slide  preparation  and  stained  it  for  flagella. 

The  central  portion  grew  much  elevated  with  folded  w^hite 
wrinkles ;  from  these  we  were  able  to  get  a  specimen  of  the  spores. 


Plate  169.     Bacillus  Meseutericiis  Frumenti 

Photomicrograph  of  a  Corn  Bacillus  found  in  a  can  of  sour  corn,  which  had 
been  sterilized  at  245  degrees  Fahrenheit  for  65  minutes.  It  produces  much  acid 
no  gas  and  curdles  the  corn  milk.  It  is  actively  motile,  propelling  itself  by  means 
of  numerous  flagella  growing  out  from  the  cell  in  all  directions.  This  is  from 
a  very  young  growth  on  corn  juice  agar,  stained  by  our  own  method,  mounted 
in  Xylol  Balsam.     Magnified  1,000  diameters. 


Plate  170,     Bacillus  Mesentericus  Frumenti 

Photomicrograph  of  the  spores  of  the  Corn  Bacillus,  shown  in  plate  169.  These 
spores  are  centrally  located  in  the  rods,  and  after  being  set  free  are  able  to 
resist  a  temperature  of  245  degrees  Fahrenheit  for  65  minutes  when  growing  in 
cans  of  corn.  Stained  with  carbol  fuchsine,  mounted  in  Xylol  Balsam,  photo- 
graphed with  acetylene  radiant  under  a  1-12  homogeneous  oil  immersion  lens, 
giving  a  magnification  of  1,000  diameters. 


432  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

which  resembled  other  varieties  previously  examined.  The  spores 
had  very  thick  walls  and  were  thus  well  protected  against  heat  or 
other  unfavorable  conditions.  This  organism  seemed  to  curdle  the 
corn  juice  giving  it  a  greyish  color,  and  the  water  seemed  to  sep- 
arate from  the  juice  quite  freely.  It  was  possible  to  detect  this 
watery  condition  by  shaking  the  along  with  one  not  so  affected. 

The  other  bacillus  corresponded  to  one  previously  described 
(see  Plate  165). 

SPOILED    CORxNT. 

The  following  letter  explains  itself: 

Mr.  E.  W.  Duckwall, 
Aspinwall,  Pa. 

Dear  sir  : — We  are  expressing  you  today,  prepaid,  four  cans, 
two  bulged,  one  good,  and  one  empty,  for  examination.  Please 
advise  us  wherein  the  trouble  lies.  Is  it  a  lack  of  sterilization, 
faulty  cans  or  our  water  supply?  We  use  a  standard  formula, 
cooking  one  hour  and  twenty  minutes  at  240°.  Our  water  supply 
comes  from  a  driven  well  178  feet  deep.  Do  you  consider  the  good 
can  safe? 

Verv  trulv  vours, 


The  four  cans  reached  the  laboratory,  but  the  contents  of  one 
had  been  lost  on  the  way.  We  punctured  the  other  swells  with  a 
sterilized  awl,  and  after  the  escape  of  fermenting  corn  juice  and 
malodorous  gases,  we  inoculated  several  Petri  dishes  and  bouillon 
tubes  with  some  of  the  juice  taken  from  the  can,  under  as  nearly 
aseptic  conditions  as  possible.  We  had  a  fine  growth  of  bacteria 
in  all  of  the  tubes  and  dishes.  After  diluting  the  bouillon  we 
streaked  several  Petri  dishes,  and  obtained  colonies  sufficiently  sep- 
arated for  isolation.  One  of  these  organisms  was  described  under 
plate  169.  The  bouillon  culture  formed  a  pellicle  on  the  surface 
and  this  became  very  much  wrinkled.  The  plate  culture  spread 
rapidly,  a  thin,  transparent  growth  of  bacteria  extending  in  all  di- 
rections from  the  line  of  inoculation.  This  organism  produced  no 
gas  in  any  of  the  cultures  made,  and  when  transplanted  into  cans 
of  corn  caused  them  to  turn  sour,  without  the  formation  of  gas  or 
swelling  of  the  can.  It  forms  spores,  centrally  located  in  the  rods, 
and  when  these  are  set  free  they  become  extremely  resistant  to 
high  temperatures  and  are  able  to  withstand  245  degrees  F.  for  65 
minutes,  and  in  this  case  withstood  a  temperature  of  240  degrees 
for  80  minutes.  This  was  the  process  mentioned  by  the  packer  in 
his  letter. 


CORN.  433 

The  other  bacilhis  formed  gas  quite  freely,  and  sulphuretted 
hydrogen  was  also  formed,  and  the  bouillon  culture  gave  the  indol 
reactions.  The  foul  odor  noticed  when  we  opened  the  can  was  due 
to  these  two  products.  The  bacillus  is  a  spore  bearing,  actively  mo- 
tile organisms  and  formed  a  pellicle  on  the  surface  of  the  bouillon, 
and  caused  the  fermentation  of  grape  sugar  bouillon  and  corn  juice. 
It  is  endowed  with  numerous  flagella.  which  grow  out  from  the 
entire  surface  of  the  cells,  and  these  are  the  cause  of  its  active  mo- 
tility. The  colonies  on  agar  are  round  and  greyish  white,  at  first 
lustrous,  then  becoming  more  wrinkled  and  folded.     The  periphery 


Plate  1 71 .     Bacillus  of  Malodorous  Corn 

Photomicrograph  of  a  bacillus  isolated  from  a  can  of  spoiled  corn  which  had 
been  processed  for  80  minutes  at  240  degrees  Fahrenheit.  This  organism  actively 
motile,  having  very  numerous  flagella  stained  by  our  special  method.  This  speci- 
men was  taken  from  a  very  young  growth  of  pure  culture  on  Agar.  Magnified 
1,200  diameters. 

is  indented  or  tufted;  the  same  general  characteristics  are  demon- 
strated in  the  streak  culture  on  the  surface  of  nutrient  agar  in 
Petri  dishes.  The  spores  are  located  nearer  one  end  of  the  rod,  and 
when  set  free  are  very  resistent  to  high  temperatures,  as  was  evident 
from  their  having  passed  through  a  process  of  240  degrees  F.  for 
80  minutes.  The  cans  inoculated  with  the  spores  of  this  organism 
were  perfectly  sterilized  when  given  a  process  of  250  degrees  F.  for 
65  minutes. 

In  sterilizing  corn  we  believe  that  250  degrees  F.  should  be 
used  in  preference  to  the  lower  temperature.  It  requires  about  50 
to  55  minutes  for  this  temperature  to  reach  the  center  of  a  No.  2 
can,  and  it  requires  about  10  minutes'  exposure  to  this  temperature 
to  insure  devitalization  of  the  spores  of  such  bacteria  as  are  shown 
in  the  accompanying  plates.     It  is  barely  possible  that  this  time 


434  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

could  be  cut  down  a  few  minutes  if  the  cans  are  agitated  during 
sterilization,  but  corn  is  almost  impervious  to  heat,  and  those  ker- 
nels which  are  nearest  the  tin  are  sterilized  in  far  less  time  than 
those  at  the  center,  so  that  agitation  would  have  a  tendency  to  bring 
the  corn  in  the  center  nearer  the  in  at  times.  A  temperature  of  250 
degrees  does  darken  the  color  a  trifle,  but  if  the  proper  cooling  pro- 
cess is  employed,  the  color  will  be  very  good,  and  while  not  as  white 
as  corn  bleached  with  sulphites,  is  good  enough  for  any  market. 
Some  of  the  cans  sent  to  the  laboratory  for  inspection  have  had  very 
good  color  after  this  process.  The  good  can  appears  to  be  all 
right ;  up  to  this  time  it  has  not  swelled  in  a  temperature  of  98  de- 
grees F. 


discoloration  o^  corn. 

Nationat,  Canners'  Laboratory, 
Aspinwall,  Pa. 

Gentlemen  : — We  are  sending  you  via  express  today  four 
cans  corn.  We  w-isli  you  to  analyze  same  and  kindly  write  us  as 
soon  as  possible  cause  for  their  being  curdled  like  and  black  in  cap 
end  of  can.  Corn  looks  good  except  on  capped  end.  Our  whole 
pack  seems  to  be  in  same  shape.  We  have  taken  these  cans  from 
four  different  w^eeks'  pack. 

Yours  very  truly. 


When  the  cans  arrived  we  placed  all  excepting  one  in  the  incu- 
bator for  a  week  in  order  to  get  a  growth  of  any  bacteria  which 
might  be  present.  After  that  time  we  removed  them  and  streaked 
a  number  of  Petri  dishes  containing  a  nutrient  agar  preparation. 
We  examined  the  juice  carefully,  but  could  find  no  trace  of  bacteria 
at  that  time.  We  naturally  thought  that  the  cans  contained  no  bac- 
teria, because  w^e  could  not  see  any  under  the  microscope,  but  we 
obtained  a  free  growth  in  the  Petri  dishes  w^ithin  twenty-four  hours. 
We  then  examined  the  cans  again  and  found  that  in  two  of  them  the 
bacteria  had  developed  wonderfully.  We  did  not  get  any  grow^th 
from  one  can,  either  in  the  can  or  in  the  dishes,  so  this  can  was 
sterile.  These  bacteria  were  strictly  aerobic,  that  is,  they  were  able 
to  grow  only  in  the  presence  of  air,  and  this  accounted  for  our  fail- 
ure to  make  them  multiply  in  the  cans  during  the  first  incubation. 
We  endeavored  to  grow  them  in  the  anaerobic  culture  apparatus, 
but  were  unsuccessful,  and  this  proved  that  they  were  strict  aerobes. 
There  w^ere  two  different  species,  one  in  can  marked  No.   i,  and 


St 


CORN.  435 

another  in  can  No.  3,  and  both  were  motile  and  spore  bearing.  We 
introduced  the  spores  into  some  cans  of  good  corn  we  have  in  the 
laboratory,  then  processed  them;  within  a  week  we  had  the  same 
discoloration  seen  in  the  originals.  This  would  indicate  that  the  bac- 
teria were  able  to  grow  as  long  as  there  was  any  oxygen  in  the  can, 
and  after  that  they  would  form  spores  and  the  rods  w^ould  dissolve, 


-      ^-  V 


^f  i 


Plate  172 

Photomicrograph  of  a  beautifully  flagellated  bacillus  which  greatly  resembles 
Bacillus  Mesentericus  Vulgatus  in  many  respects,  but  is  an  obligative  aerobe. 
Isolated  from  a  can  of  corn,  which  showed  dark  discoloration,  due  to  the  action 
of  sulphuretted  hydrogen  on  the  metal  of  the  can.  Slide  preparation  made  from 
a  six  hours'  growth  on  agar.  The  numerous  fiagella  are  stained  by  our  own 
special  method,  and  photographed  through  the  microscope  through  a  1-12  homo- 
geneous oil  immersion  objective  and  No.  6  compensating  eyepiece,  using  acety- 
lene radiant.     Magnified  1,200  diameters, 

leaving  only  free  spores  which  we  were  unable  to  detect  positively 
in  the  juice  under  the  microscope. 

The  bacillus  found  in  can  No.  i  was  beautifully  flagellated, 
which  gave  it  very  active  motility.  It  is  strictly  aerobic  and  differs 
from  any  bacillus  thus  far  isolated  by  us.  In  appearance  it  greatly 
resembles  bacillus  mesentericus  vulgatus.  It  forms  long  chains  and 
some  of  these  would  be  motile  and  flagellated.  After  a  time  spores 
would  form  near  one  end  of  the  rods  and  the  rods  would  dissolve 
rapidly,  leaving  the  spores  free. 


436  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

Plate  culture  on  agar. — Very  rapid  growth  with  scalloped 
border.  A  thin  almost  transparent  film  of  young  motile  bacteria 
extended  in  all  directions  and  soon  reaches  the  w^alls  of  the  dish. 
From  this  almost  invisible  growth  line  preparation  may  be  obtained- 
for  the  demonstration  of  the  flagella.  After  the  growth  becomes 
quite  visible  it  is  slimy,  and  in  this  resembles  the  potato  bacillus.  It 
forms  a  pellicle  on  the  surface  of  bouillon,  but  does  not  produce  any 
gas.  It  forms  a  small  amount  of  sulphuretted  hydrogen,  which  is 
determined  as  follows :  The  agar  is  colored  a  light  yellow  with 
ferritatrate  made  alkaline  with  sodium  carbonate :  the  bacteria  cause 


Plate  173 

Photomicrograph  of  the  thick  walled  spores  of  the  bacillus  shown  in  plate  172. 
The  spores  are  the  seed  forms  and  a,re  exceedingly  resistant  to  heat  and  other 
unfavorable  conditions.  These  are  the  forms  of  the  bacillus,  when  forced  into  a 
resting  state.  In  a  favorable  place  they  will  again  form  the  bacilli,  providing  air 
is  present.  This  photograph  was  taken  from  a  slide  preparation  of  a  four  days' 
growth  of  a  pure  culture  on   agar.     Magnified  1,500  diameters. 


this  to  turn  black  if  sulphuretted  hydrogen  is  produced.  It  is  this 
substance  which  gives  the  corn  the  dark  discoloration  seen  fre- 
quently and  was  the  direct  cause  in  the  case  before  us. 

The  spores  of  this  organism  are  very  resistant  to  heat,  because 
they  are  thick  membraned.  A  close  study  of  the  plate  shows  this 
characteristic.  Nearly  every  rod  forms  spores  and  when  we  stained 
an  old  culture  we  rarely  found  any  rods  at  all,  they  all  having  gone 
to  spores. 

This  organism  grows  only  in  the  presence  of  air,  and  when 
forced  into  an  anaerobic  condition  forms  spores  and  goes  into  a  rest- 
ing state.     For  this  reason  it  will  not  continue  to  grow  in  the  sealed 


CORN. 


437 


cans  after  the  supply  of  oxygen  is  exhausted,  consequently  will  not 
cause  very  great  changes. 

The  bacillus  isolated  from  the  can  marked  No.  3,  was  different 
in  its  manner  of  growth.  When  streaked  on  agar  it  grew  only  along 
the  line  of  inoculation  and  did  not  send  out  the  invisible  film  seen  in 
the  other  culture.  On  ordinary  agar  we  had  difficulty  in  getting  a 
confluent  growth:  it  seemed  to  form  colonies  and  resembled 
Hueppe's  bacillus  butyricus  in  this  respect.  It  did  not  form  any 
slime,  but  gave  rise  to  spores  rapidly.     These  spores  are  centrally 


Plate  174 

Photomicrograph  of  a  very  active  bacillus  greatly  resembling  Hueppe's  Bacil- 
lus butyricus  in  its  manner  of  growth  and  chemical  products,  but  is  an  obligative 
aerobe.  Culture  obtained  from  a  can  of  discolored  corn.  It  produces  no  gas 
but  forms  small  amounts  of  sulphuretted  hydrogen.  It  also  produces  butyric  acid. 
Slide  preparation  was  made  from  a  very  young  growth  on  agar  and  the  numerous 
flagella  were  demonstrated  by  our  special  method  and  then  photographed  through 
the  microscope  using   acetylene  radient.     Magnified  1,200   diameters. 


located  in  the  rods  as  a  rule,  although  some  of  them  were  quite  near 
the  ends  of  the  rods.  There  were  a  great  many  barren  rods  in  the 
cultures  we  made,  and  many  rods  which  did  not  form  spores  at 
all,  as  shown  by  the  plate.  The  spores  are  quite  small,  and  the 
membrane  does  not  seem  to  be  as  thick  as  that  of  the  other  species. 
This  organism  is  also  strictly  aerobic,  and  cannot  grow  where  oxy- 
gen is  excluded.     We  went  through  the  same  technique  as  described 


438  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

previously  and  learned  that  sulphuretted  hydrogen  was  produced, 
but  only  in  small  amounts.  It  produced  no  indol  or  other  foul  pro- 
duct and  formed  no  gas.  Like  the  other  species  it  developed  and 
grew  as  long  as  there  was  any  oxygen  in  the  can  and  then  went  into 
a  resting  state. 

These  are  the  first  strictly  aerobic  bacteria  we  have  ever  iso- 
lated from  canned  corn,  all  the  others  have  been  facultative  anae- 
robes ;  that  is,  they  were  able  to  grow  in  the  presence  or  absence  of 
oxygen.     That  class  of  bacteria  would  of  course  continue  to  grow 


riate  175 

Photomicrograph  of  the  spores  and  barren  rods  of  bacillus  shown  in  plate  174. 
The  spores  are  smaller  than  those  of  the  first  bacillus  obtained  from  can  No.  1, 
and  the  walls  of  the  spores  are  more  delicate.  They  are  able,  however,  to  with- 
stand much  heat.  From  four  days  agar  culture,  stained  with  carbol  fuchsin.  Mag- 
nified 1,500  diameters. 


and  completely  ruin  the  goods.  While  these  have  interfered  some- 
what with  the  appearance,  they  cannot  proceed  and  the  goods  will 
not  therefore  deteriorate  any  further. 

We  would  recommend  a  process  of  250  degrees  F.  for  65  min- 
utes, which  will  be  sufficient,  we  believe,  to  insure  perfect  steriliza- 
tion. 

SOUR   CORN. 

A  packer  called  at  the  laboratory  and  stated  that  he  had  been 
losing  quite  heavily  on  one  particular  brand  of  his  corn  on  account 
of  sourness.  He  stated  that  there  were  other  canners  in  his  im- 
mediate vicinitv  who  were  also  havinq-  similar  trouble. 


CORN.  439 

This  packer  puts  up  a  special  grade  of  corn  and  his  loss  was 
confined  to  this  grade.  He  said  that  he  had  not  lost  any  of  the  reg- 
ular goods  from  "sours."  The  special  grade  he  had  put  up  in  the  us- 
ual manner  and  used  granulated  sugar  as  a  sweetener,  where  form- 
erly he  liad  used  saccharin.  He  said  that  when  he  opened  some  of 
the  cans  they  were  quite  sour  ^md  some  had  a  putrefying  odor. 
None  of  the  cans  showed  any  signs  of  swelling.  He  processed  these 
goods  55  minutes  at  240  degrees  Fahr.  and  allowed  about  20  min- 
utes' time  for  heating  up  to  that  temperature.  He  was  very  anxious 
to  sort  out  the  bad  cans  so  that  he  might  dispose  of  all  that  were 
good.  He  had  tried  in  various  ways  to  do  this,  but  none  of  them 
proved  reliable,  so  he  came  to  the  laboratory  for  advice. 

We  requested  him  to  send  us  a  case  of  this  corn  for  bacterio- 
logical examination.  This  he  did.  We  advised  him  in  the  mean- 
time to  heat  his  cans  in  boiling  water  until  they  all  swelled.  This 
we  thought  could  be  done  in  about  20  to  30  minutes,  and  our  idea 
was  to  chill  the  cans  quickly  wdth  cold  water  and  all  whose  ends 
snapped  back  within  a  few  minutes  were  to  be  sorted  out  as  good 
cans  and  all  which  failed  to  snap  back  were  to  be  considered  bad 
cans.  He  acted  on  our  advice  and  reported  that  among  the  cans 
whose  ends  snapped  back  quickly,  he  found  quite  a  number  which 
were  sour,  and  among  those  which  he  had  set  aside  as  bad,  he  found 
quite  a  number  which  showed  no  evidence  of  sourness,  then  he 
stated  that  he  was  opening  the  cans  now,  and  w^as  tasting  them, 
but  he  had  taken  a  large  number  of  cans  which  had  been  tasted,  re- 
capped them  and  then  put  them  into  the  retorts  and  given  them  a 
process  of  250  degrees  for  6^  minutes.  He  stated  that  on  opening 
some  of  these  cans  he  found  that  they  were  very  much  discolored 
by  the  extra  amount  of  cooking  and  also  that  quite  a  number  had 
developed  sourness  in  the  process.  This  mystified  him  very  much, 
but  I  told  him  that  the  sourness  had  started  in  the  center  of  the 
cans  and  had  probably  not  extended  to  the  surface,  therefore  it 
could  not  be  detected  by  those  who  had  tasted  the  corn  before  the 
cans  were  reprocessed.  The  processing  thoroughly  mixed  the  acid 
so  that  it  was  easily  detected  afterwards. 

I  told  him  that  where  corn  soured  on  account  of  the  bacteria 
developing  in  the  cans  after  incomplete  sterilization,  it  usually 
started  in  the  center  of  the  cans,  because  at  that  point  the  heat  had 
not  been  sufficient  to  destroy  them.  During  the  mixing  of  the 
corn,  prior  to  the  filling,  the  spores  of  the  bacteria  peculiar  to  corn 
are  mixed  in  w^ith  the  mass  so  that  there  are  many  in  the  center  of 
the  cans.  Some  spores  are  destroyed  at  even  moderate  tempera- 
tures, but  others  will  survive  cooking  for  a  long  time,  and  unless 
the  temperature  used  in  sterilization  is  sufficiently  high  and  pro- 
longed to  reach  the  resistant  spore  forms  in  the  center  of  the  cans 


440  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

they  will  afterwards  develop  and  the  sourness  will  begin  at  the  point 
where  the  bacteria  began  to  grow. 

This  cleared  the  matter  up  for  him  and  he  decided  to  subject 
all  of  his  cans  to  a  high  temperature  for  a  sufficient  time  to  heat 
them  through  to  the  center,  so  he  used  a  temperature  of  240  degrees 
Fahr.  for  65  minutes  and  this  heat  thoroughly  penetrated  the  cans 
so  that  when  they  w^ere  removed  both  ends  bulged  out.  The  color 
of  these  goods  was  very  fair  considering  the  amount  of  cooking 
they  had  received,  in  fact,  it  was  almost  impossible  to  detect  any 
difference  in  the  color  from  that  of  the  original. 

The  question  now  arose  in  the  packer's  mind  whether  this  sec- 
ond cooking  would  be  sufficient  to  prevent  bacterial  action  in  those 
cans  which  he  had  sorted  out  as  good ;  also  in  those  cans  which  he 
had  sorted  out  and  styled  ''push-backs."  In  order  to  determine 
this  point  he  sent  some  of  the  latter  into  the  laboratory.  We  in- 
oculated Petri  dishes  and  bouillon  with  some  of  the  juice,  and  after 
thirty-six  hours  we  failed  to  get  any  growth.  It  would  seem  there- 
fore that  the  second  cooking  had  completely  sterilized  the  pans. 
This  was  probably  due  to  the  fact  that  there  were  no  spore  forms 
present,  all  having  developed  into  full-grown  bacteria  or  vegetating 
forms,  which  are  easily  destroyed  even  at  180  degrees  Fahr. 

This  packer  said  that  about  40  per  cent  of  the  cans  had  soured, 
and  he  was  very  much  at  a  loss  to  know  why  that  per  cent  had 
soured  and  the  other  60  per  cent  were  apparently  good.  We  opened 
quite  a, number  of  cans  in  his  presence  and  examined  the  consist- 
ency. We  found  that  the  consistency  varied  considerabl}^  Some 
cans  were  very  solid,  having  little  fluid;  others  were  quite  moist, 
so  that  the  fluid  flowed  back  and  forth  between  the  particles  of  corn ; 
and  there  were  still  others'  whose  consistency  varied  between  these 
two  extremes.  It  is  quite  reasonable  to  suppose  that  the  solid- 
packed  corn  would  be  less  penetrable  to  heat  than  that  which  was 
more  moist,  but  in  the  first  place  the  temperature  of  240  degrees 
Fahr.  for  55  minutes  would  not  be  a  safe  process  for  corn,  and  it 
is  surprising  that  it  did  not  all  sour.  We  are  of  the  opinion  that 
this  Avould  have  been  the  result  finally,  but  owing  to  the  temperature 
of  the  corn  room  being  quite  low,  the  putrefactive  action  was  nec- 
essarily slow.  Then  again,  the  process  given  might  have  been  suf- 
ficient in  some  cases  where  the  spores  were  of  less  resistant  char- 
acter. The  process  for  corn  should  be  250  degrees  Fahr.  for  65 
minutes,  not  counting  the  time  required  to  reach  that  degree  of  heat. 
By  the  calcium  system,  time  for  raising  this  temperature  would 
have  to  be  allowed,  so  that  the  total  time  for  carrying  cans  through 
the  calcium  solution  would  be  about  70  to  75  minutes. 

The  following  method  of  testing  to  separate  sour  from  sweet 
corn  has  been  used  with  much  success  by  some  packers,  and  while 


CORN.  441 

we  are  not  called  upon  to  guarantee  its  infallability,  we  have  added 
an  explanation  of  points  wdiich  would  seem  to  indicate  its  reason- 
ableness. We  should,  however,  be  pleased  to  receive  from  any  of 
our  packer  friends  any  data  based  on  their  experiences  which  would 
tend  to  throw  any  further  light  on  this  general  subject. 

TEST   FOR   SEPARATING   SOUR   EROM    SWEET    CORN. 

Corn  to  be  taken  cold  and  put  in  steam  kettles.  Temperature 
to  be  run  up  in  twenty  minutes  to  240  degrees;  hold  for  sixty-five 
minutes  at  that  point.  Take  out  quickly  as  possible  and  put  in  cold 
water  for  five  minutes. 

Take  crates  in  warehouse,  and  by  hand,  lay  cans  on  floor  in 
rows  carefully,  so  each  end  of  can  is  exposed  to  view.  After  stand- 
ing in  warehouse  for  four  hours  (temperature  in  warehouse  to  be 
50  degrees),  go  over  cans  and  pick  out  all  that  have  collapsed  on 
both  ends.  Quickly  run  them  through  the  hot  tank  at  148  degrees 
at  feed  end  and  not  over  151  degrees  at  outlet  of  tank.  Speed  of 
cans  through  tanks,  seven  minutes. 

Such  cans  as  pass  through  the  hot  tank  undeveloped  or  not 
swelled  to  be  set  aside  and  called  No.  i  collapse.  Such  cans  as 
develop  or  swell  when  passing  through  hot  tank  to  be  set  aside 
and  called  No.  2  collapse. 

Then  go  over  balances  of  cans  in  warehouse  immediately,  and 
all  cans  that  have  swelled  on  one  end  only,  or  collapse  with  the 
pressure  of  the  finger,  put  all  such  cans  through  the  hot  tank,  same 
temperature  and  speed  as  collapses.  All  cans  that  pass  through  un- 
developed to  be  kept  separate  and  called  No.  i  push  backs,  and  all 
cans  that  develop  or  swell  to  be  set  aside  and  called  No.  2  push 
backs. 

After  this  second  overhauling,  all  cans  that  remain  on  w^are- 
house  floor  swelled  at  both  ends  to  be  set  aside  as  spoiled  and  of  no 
value. 

All  cans  known  as  No.  i  collapses  to  be  considered  first  qual- 
ity, and  all  cans  known  as  No.  i  push  backs,  to  be  considered  first 
quality.  All  cans  from  No.  2  collapses,  to  be  considered  second 
grade  corn  and  salable. 

No.  I  collapses,  No.  i  push  backs  and  No.  2  collapses,  to  be 
cooled  immediately  after  coming  out  of  hot  tank,  by  laying  on  plat- 
form outside  of  building ;  should  lay  sufficient  time  to  become  thor- 
oughly cold,  not  frozen. 

Greatest  care  possible  must  be  exercised  in  the  handling  of  the 
cans  so  as  not  to  prematurely  do  anything  that  will  cause  them  to 
collapse  on  either  end ;  the  collapsing-  must  be  natural,  with  the  ex- 
ception that  on  the  second  over-hauling,  such  cans  as  are  collapsed 


442  CANNING  AND  PRESERVING  OP  FOOD  PRODUCTS. 

on  one  end  only,  to  be  forced  in;  that  is,  such  cans  as  will  yield  to 
the  slight  pressure  of  the  fingers. 

Referring  to  the  above  mentioned  system  of  sorting  out  sour 
corn  from  the  good,  we  will  explain  how  this  may  be  judged  as  a 
reasonable  method.  In  Plate  176  we  have  reproduced  the  bacteria 
which  had  caused  the  sour  corn.  These  belong  to  a  certain  class  of 
microbes  which  do  not  form  gas;  they  attack  the  carbohydrates, 
principally  the  sugar  of  the  corn,  converting  it  into  lactic  acid,  and 
also  forming  other  complex  substances  such  as  indol,  and  sulphur- 
etted hydrogen  which  is  taken  up  by  the  fluid  and  does  not  volatil- 


Plate  176 

Photomicrograph  of  the  corn  bacillus  which  produces  no  gas;  it  breaks  up  the 
sugar  into  lactic  acid,  butyric  acid  and  sulphuretted  hydrogen,  consequently  will 
cause  "sour  corn"  without  swelling  the  cans.  This  organism  differs  from  all 
classified  bacteria  in  several  respects,  although  resembling  Mesentericus  in  the 
heat  resisting  power  of  its  spores.  It  is  a  facultative  anaerobe,  actively  motile. 
Flagella  are  demonstrated  by  our  own  method.  Magnified  1,500  diameters. 

ize  into  gas  except  under  the  influence  of  heat.  These  chemical 
changes  may  take  place  in  a  vacuum  and  no  gas  is  produced,  and 
there  is  no  evidence  whatever  from  the  external  appearance  of  the 
can  of  any  such  changes.  When  the  packer  heated  his  cans  so  that 
the  high  temperature  penetrated  to  the  center,  the  hydrogen  sulphdie 
was  driven  into  the  form  of  a  gas,  and  owing  to  this  characteristic 
property,  the  bad  cans  were  quite  easily  sorted  out  while  the  good 
cans  which  contained  none  of  the  (HoS)  soon  snapped  back  to 
their  normal  condition. 

During  our  conversation  the  packer  asked  me  if  it  was  not 
possible  that  the  granulated  sugar  he  had  used  in  this  corn,  might 
have  had  something  to  do  with  the  sourinof.     He  stated  that  he  had 


CORN.  443 

formerly  used  saccharin  or  "sugar  crystals/'  as  they  are  called,  and 
he  had  never  had  any  such  loss.  He  stated  that  it  had  been  repre- 
sented to  him  that  sugar  would  cause  the  souring  of  peas  and  corn, 
and  he  also  stated  that  a  certain  salesman  of  chemicals  had  advised 
him  never  to  use  granulated  sugar,  or  if  he  decided  to  use  sugar 
at  all,  he  ought  to  use  "Franklin  A"  or  Confectioners'  "A;"  that 
granulated  sugar  contained  impurities  which  might  cause  the  sour- 
ing of  his  good.  All  such  talk  as  this  is  mere  theory.  There  is 
nothing  in  the  facts  to  warrant  such  statements.  The  chemical  re- 
ports on  granulated  sugar  show  that  it  runs  from  98  to  100  per  cent 
pure,  and  a  small  amount  of  impurity  would  have  nothing  whatever 
to  do  with  the  spoilage  of  such  goods  as  corn  or  peas. 


Plate  177 

Photomicrograph  of  the  spore-bearing  rods  of  the  corn  bacillus  shown  in  pre- 
ceding plate.  The  rods  show  the  spores  located  in  the  center.  The  spores  are 
extremely  resistant  to  high  temperatures.  The  bacilli  form  chains  of  several  rods. 
This  photomicrograph  was  taken  from  a  48-hour  growth  on  agar,  slightly  stained 
with  carbol  fuchsine,  mounted  and  photographed  through  a  rcticroscope  using 
Spencer  1-12  oil  immersion  objective  and  acetylene  radiant.  Magnified  1,590 
diameters. 

/ 

There  are  no  extremely  resistant  forms  of  bacteria  identified 
with  the  fermentation  of  sugar.  Molds  and  yeasts  will  cause  a  fer- 
mentation of  granulated  sugar  when  combined  with  fruit  juices, 
fruit  pulps  and  tomato  products,  but  these  forms  of  life  are  easily 
destroyed  at  even  boiling  temperature.  Granulated  sugar  is  in  it- 
self a  preservative,  and  could  not  increase  the  risk  of  souring  in 
g'oods  which  must  receive  as  high  a  temperature  as  that  which  is 
given  sugar  corn  for  complete  sterilization.  The  cause  of  spoilage 
in  canned  corn  after  sterilization,  is  always  traceable  to  spore-bear- 
ing bacteria  which  are  present  in  the  corn  itself  before  canning. 
The  sugar  could  not  have  any  influence  one  way  or  the  other.  It 
has  been  claimed  that  saccharin  was  a  preservative  and  for  that 
reason  was  preferable  to  granulated  sugar,  because  it  exercised 
antiseptic  power  on  the  bacteria,  but  this  is  not  the  case  simply  be- 


444  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

cause  saccharin  is  used  onjy  in  very  limited  quantities,  quantities 
so  small  that  it  could  not  have  any  antiseptic  intiuence. 

Preservatives  are  valuable  only  when  used  in  sufficient  amounts 
to  prevent  the  multiplication  of  bacteria ;  when  used  in  small 
amounts  they  act  rather  as  a  stimulant,  and  are  used  sometimes  in 
our  culture  media  to  stimulate  the  growth  of  certain  species  of  bac- 
teria. Salic3dic  acid  is  frequently  used  in  the  isolation  of  the  ty- 
phoid bacillus  which  grows  readily  when  only  a  small  amount  of 
this  chemical  is  employed.  Saccharin  even  in  very  strong  solu- 
tions has  very  little  antiseptic  power,  and  in  the  amount  used  for 
sweetening  corn  and  peas  its  influence  would  be  rather  stimulative 
than  antiseptic. 

Speaking  of  saccharin,  we  recall  the  heated  controversy  which 
took  place  at  the  International  Food  Congress  in  St.  Louis  between 
those  who  had  investigated  its  action  pharmacologically,  and  the 
Food  Commissioners.  The  Food  Commissioners  looked  upon  sac- 
charin as  a  substitute  for  sugar,  and  they  claim  that  it  has  no  food 
value,  that  it  passes  through  the  body  in  an  unchanged  condition, 
and  that  if  used  for  a  long  time  it  is  apt  to  cause  nephritis.  That 
it  does  pass  though  the  bod}^  in  an  unchanged  condition,  and  that 
it  is  not  a  food,  we  cannot  deny.  As  to  its  effect  upon  the  human 
body,  we  cannot  dispute  their  claims,  because  we  have  never  made 
any  experiments  to  determine  the  correctness  of  these  assertions. 
We  would  advise  packers,  if  we  might  be  permitted  to  make  a  sug- 
gestion, that  they  be  guarded  in  their  use  of  saccharin  this  com- 
ing season,  because  the  food  commissioners  are  liable  to  enter  suits 
against  any  grocers  who  sell  canned  goods  containing  this  artificial 
sv;eetener,  and  the  packers  wnll  have  to  come  forward  then  and  de- 
fend their  customers. 

We  are  also  under  the  impression,  though  we  cannot  state  it 
as  a  positive  fact,  that  saccharin  would  oxydize  into  salicylic  acid 
in  some  cases  where  high  temperatures  are  used  to  accomplish  steril- 
ization of  canned  goods.  It  is  not  a  very  difficult  matter  to  deter- 
mine the  presence  of  saccharin  in  canned  corn  and  peas,  the  chemi- 
cal technique  being  similar  to  that  used  for  determining  the  presence 
of  salicylic  acid,  namely,  a  chloroform  or  ether  extract  is  made  and 
the  residue  from  this  is  converted  into  salicylic  acid  by  subjecting 
it  to  a  high  temperature,  250  degrees  C,  with  sodium  hydroxide. 
The  sodium  salicylate  thus  formed  is  easily  detected  by  the  ferric 
chloride  test  and  in  order  to  confirm  this  the  residue  from  another 
extraction  is  heated  with  resorcin  and  a  few  drops  of  sulphuric  acid 
in  a  test  tube  till  it  begins  to  swell  up.  Several  times  heating  and 
then  neutralizing  with  sodium  hydroxide  will  give  a  red-green 
fluorescence  where  saccharin  is  present. 


CORN.  445 

ANOTHER  casl:. 

We  were  informed  that  one  packer  claimed  to  have  a  great 
deal  of  sour  corn  after  using  a  process  of  250  degrees  Fahr.  for  70 
minutes,  but  this  does  not  seem  likely  to  me.  If  such  were  the  case, 
his  corn  must  have  been  entirely  too  dry  or  solid-packed,  and  this  is 
a  very  important  matter.  It  must  not  be  overlooked  that  sour  corn 
is  not  always  due  to  imperfect  sterilization.  We  all  know  that  corn 
will  sour  if  allowed  to  remain  standing  in  piles  before  canning.  I 
was  told  of  the  condition  in  some  of  the  factories  which  had  consid- 
erable sour  corn.  It  was  something  like  this :  They  were  sorting 
their  corn  after  it  was  husked,  into  two  grades,  a  No.  i  and  No.  2. 
The  No.  I  grade  was  run  through  the  cutters,  cooked,  filled,  capped 
and  processed  promptly,  while  the  No.  2  was  carried  off  to  one  side 
and  the  husked  ears  were  piled  up  in  great  heaps.  This  remained 
in  this  condition  until  after  completing  the  run  on  No.  i ;  then  the 
No.  2  was  run  through  the  machine  and  canned.  A  great  many 
''sours"  developed  in  this  No.  2,  and  it  is  no  wonder,  because  the 
lactic  acid  bacteria  would  develop  readily  in  the  center  of  such  piles 
and  when  lactic  acid  is  formed  it  cannot  be  eliminated  by  any  cook- 
ing process. 

A  GAS  PRODUCING  ORGANISM   IN   CANNED  CORN. 

AVe  examined  a  can  of  corn  which  had  received  about  half  the 
process  usually  given  corn.  Our  idea  was  to  isolate  all  the  bacteria 
that  usually  infest  corn,  and  we  expected  to  find  several  different 
varieties,  but  only  one  species  developed,  which  was  an  anaerobe. 
This  germ  produced  great  quantities  of  gas  and  the  can  swelled  up 
until  it  was  nearly  ready  to  burst  when  we  punctured  it  and  made 
plate  cultures  of  the  bacteria.  While  the  germ  was  an  anaerobe  we 
could  get  a  small  growth  when  cultivated  in  the  presence  of  air  but 
it  grew  better  when  all  oxygen  was  excluded.  The  gas  produced  by 
this  organism  was  sulphuretted  hydrogen,  which  we  detected  by 
the  sodium  ferri-tartrate  test.  V/e  also  found  that  this  germ  pro- 
duced phenol,  which  probably  accounted  for  the  fact  that  no  other 
organisms  were  present,  the  phenol  having  acted  as  an  antiseptic. 
This  organism  produces  spores  rapidly  in  the  incubator  at  98  de- 
grees Fahr.,  and  while  these  spores  are  heat-resisting,  they  are  not 
to  be  compared  with  those  of  the  bacteria  which  produce  no  gas. 

One  peculiarity  of  this  germ  has  induced  us  to  mention  the  ex- 
periment in  this  issue,  namely,  its  production  of  phenol;  and  there 
are  quite  a  number  of  other  bacteria  which  produce  the  same  sub- 
stance, and  goods  in  which  they  are  thriving  will  respond  to  the  fer- 
ric chloride  test  for  salicylic  acid.  We  do  not  believe  any  packers 
ever  use  salicvlic  acid  in  canned  corn,  but  we  have  seen  some  of  the 


446 


CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


Plate  178.     Bacillus  1  rumeiiti  Phenolgenus 

Photomicrograph  of  a  corn  bacillus  which  produces  much  gas.  It  causes  sour- 
ness, decomposing  the  sugar  into  acids  and  carbonic  acid  gas.  It  is  a  very  thin, 
short  bacillus,  having  numerous  flagella,  which  give  it  active  motility.  Isolated 
from   imperfectly  sterilized  corn.     It  is  an  anaerobe.     Magnified   1,200   diameters. 


Plate  179.     Bacillus  Frumenti  Phenolgenvis 


Photomicrograph  of  the  spore-forms  of  the  gas  forming  corn  bacillus  shown 
in  plate  178.  The  spores  are  small  and  centrally  located  in  the  cells,  and  are 
heat  resisting,  although  not  as  much,  so  as  those  shown  in  plate  177.  Stained 
lightly  with  carbol  fuchsine.     Magnified  1,200  diameters. 


CORN.  447 

reports  from  the  agricultural  chemists,  in  which  they  claim  to  have 
found  salicylic  acid  in  canned  corn,  and  we  mention  the  results  we 
obtained  with  this  bacillus  as  a  possible  source  of  phenol-like  bodies 
sometimes  found  in  canned  corn. 

what  caused  cans  of  corn  to  burst. 

National  Canners'  Laboratory, 
Aspinwall,  Pa. 

GentIvEmen  : — We  are  sending  you  by  express  today  a  num- 
ber of  cans  of  corn,  some  of  the  cans  being  swollen  and  some  bursted 
at  the  seam.  We  desire  that  you  analyze  the  contents  of  these  cans 
and  determine  the  cause  of  their  swelling  and  bursting.  They  were 
supposed  to  have  received  250°  Fahr.,  for  the  regular  length  of 
time. 

The  point  which  we  are  particularly  anxious  to  learn  is  whether 
the  sw^elling  and  bursting  of  these  cans  is  due  to  imperfect  steriliza- 
tion or  to  a  leaky  condition  of  the  cans.  We  have  gathered  from 
your  bacteriological  work  along  these  lines  that  it  is  possible  to  de- 
termine from  the  nature  of  the  bacteria  present  in  canned  goods 
whether  they  are  there  because  of  incomplete  sterilization  or  whether 
they  had  gained  entrance  through  a  leak  in  the  can. 

Kindly  investigate  this  matter  thoroughly  and  let  us  have  your 
report  at  the  earliest  possible  moment.  Thanking  you  in  advance 
and  awaiting  your  reply,  we  are. 

Yours  very  trul}^ 


The  two  cases  of  swelled  and  bursted  cans  of  corn  were  re- 
ceived at  the  National  Canners'  Laboratory  and  report  on  sam.e  is 
here  submitted : 

A  large  per  cent  of  the  cans  were  burst  and  the  contents  gone. 
Some  of  the  cans  were  burst  on  the  side  seam,  some  at  the  tops  and 
bottoms  and  others  had  the  tops  and  bottoms  completely  torn  off, 
not  where  they  were  soldered,  but  where  they  were  bent.  The  pres- 
sure necessary  to  produce  this  condition  of  affairs  must  have  been 
enormous,  probably  35  or  40  pounds  to  the  square  inch.  There 
wxre  also  quite  a  number  of  cans  which  were  swelled  at  both  ends 
and  from  general  appearance  did  not  leak.  A  test  was  made  with 
pressure  on  one  of  these  swelled  cans  as  follows :  A  hole  was  cut 
in  the  cap  and  the  putrefied  corn  was  shaken  out  and  a  piece  of  pipe 
was  attached  to  the  can  and  soldered  perfectly  tight  and  this  pipe 
was  connected  with  a  steam  autoclav  and  the  pressure  w^as  raised 
to  30  pounds  without  bursting*  the  can.     There  was  no  evidence  of 


448  CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 

any  leak  in  the  can.     A  microscopical  examination  of  the  seams 
showed  no  imperfections. 

In  order  to  determine  whether  these  cans  had  spoiled  from  bac- 
teria which  had  not  been  destroyed  in  the  sterilizing  process,  or 
by  bacteria  which  had  gained  entrance  through  some  possible  leak, 
it  was  necessary  to  isolate  and  study  the  nature  of  the  germs  pre- 
sent, and  then  form  definite  conclusions  from  the  results  of  the  bac- 
teriological work.  A  number  of  Petri  dishes,  about  thirty  in  all, 
were  streaked  with  the  juice  of  the  corn  from  a  half  dozen  swelled 
cans  and  these  were  placed  in  the  incubator.  A  large  number  of 
tubes  containing  2  per  cent  glucose  agar  and  2  per  cent  glucose 
bouillon  were  also  inoculated  at  the  same  time,  and  these  were  placed 


Plate  180 

Photograph  of  a  can  which  had  burst  from  the  pressure  of  gas  generated  in 
the  corn  by  anaerobic  spore-bearing  bacteiia.  One  of  these  cans  was  tested  up 
to  30  pounds  pressure,  so  that  the  power  necessary  to  burst  the  seam  and  split 
the  top  and  bottom  must  have  been  enormous. 

in  an  anaerobic  culture  apparatus.  The  juice  from  the  corn  was 
obtained  from  the  swelled  cans  under  aseptic  conditions  in  the  fol- 
lowing manner :  A  Bunsen  liame  was  held  so  that  it  would  strike 
the  tin  and  a  hole  was  punched  through  the  tin  with  a  sterilized  awl 
directly  in  the  flame.  In  every  case  the  evolution  of  gas  was  enor- 
mous and  took  fire  in  some  cases,  which  showed  the  presence  of 
hydrogen.  Test  papers  also  showed  the  presence  of  phosphoretted 
and  sulphuretted  hydrogen;  the  odor  was  abominable.  With  a 
platinum  needle  previously  sterilized  to  whiteness  in  the  flame, 
transfers  were  made  of  the  corn  juice  to  the  tubes  of  agar  and  bouil- 
lon previously  mentioned.  It  often  happens  that  the  bacteria  which 
produce  such  large  quantities  of  gas  belong  to  the  anaerobic  species ; 
that  is  to  say,  they  will  not  grow  in  the  presence  of  atmosphere,  the 
oxygen  in  the  atmosphere  being  poisonous  to  them ;  therefore  it  is 


CORN. 


449 


necessary  to  entirely  exclude  oxygen,  either  by  replacing  it  with 
another  gas,  such  as  hydrogen,  or  by  absorbing  it  with  chemicals, 
such  as  pyrogallic  acid  neutralized  with  sodium  hydroxide. 

Anaerobic  bacteria,  as  a  rule,  are  found  in  the  soil  and  upon 
vegetable  and  decomposing  organic  matter.  They  are  generally 
spore-bearing  organisms  and  are  not  freely  distributed  in  the  air 
and  are  not  likely  to  gain  entrance  to  a  can  through  a  leak.  When- 
ever canned  vegetables  are  spoiled  by  bacteria  which  gain  entrance 
through  leaks  in  the  cans  there  are  two  or  three  varieties,  one  or 
more  of  which  are  always  present.  In  fact,  the  lactic  acid  bacteria 
have  been  found  in  all  leaks  so  far  examined  in  the  laboratory. 


Plate  181 

Photograph  showing  method  of  testing  the  can.  The  can  shown  was  a  "swell" 
containing  corn.  The  can  was  opened,  the  spoiled  corn  was  washed  out  and  a 
pipe  was  soldered  in  the  opening  and  connected  with  a  steam  autoclay  and  the 
pressure  run  up  to  30  pounds  without  bursting  the  can  or  showing  any  leak,  thus 
proving  that  the  soldering  was  good  and  that  the  putrefaction  of  the  corn  was 
due  to  bacteria  which  had  not  been  destroyed  in  the  process  of  sterilization. 


An  examination  was  made  of  the  juice  from  the  cans  in  ques- 
tion, and  no  lactic  acid  or  acetic  acid  bacteria,  no  molds,  yeasts  or 
micrococci  could  be  detected  with  the  m^icroscope,  but  in  all  cases 
there  were  present  large  numbers  of  motile  bacteria.  Each  can 
seemed  to  have  a  pure  culture  of  these  germs,  although  there  were 
two  distinct  species,  in  the  different  cans,  one  more  actively  motile 
than  the  other.  The  Petri  dishes  which  were  inoculated  with  the 
juice  were  examined  from  time  to  time,  but  in  no  case  was  a  single 
colony  of  bacteria  obtained.  These  Petri  dishes  were  incubated 
at  98  degrees  Fahrenheit  in  the  presence  of  free  atmosphere.  The 
results  were  far  different  with  the  tubes  of  glucose  agar  and  bouil- 


450 


CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


Ion  in  the  anaerobic  apparatus.  The  agar  was  literally  split  all 
to  pieces  by  the  force  of  the  gas  generated  and  the  glucose  bouillon 
fermented  freely.  The  cultures  of  the  bacteria  in  all  cases  were 
pure,  although  there  were  two  different  species. 


Di:SCRIPTlON  OF  BACTERIA. 


Plate  shows  young,  vegetating  rods  which  are  stained  by  a 
special  method  to  demonstrate  the  organs  of  locomotion.  The 
rods  are  thin,  three  to  five  microns  long  and  0.3  to  0.5  of  a  micron 
wide,  curly  resembling  tetanus.   (A  micron  is  equal  to  .025  of  an 


Plate  182 

Photomicrograph,  showing  the  curly  flagella  of  the  anaerobic  Bacillus  Buty- 
ricus  Frumenti,  obtained  from  a  can  of  swelled  corn.  Some  of  the  rods  have 
the  terminal  spores  and  still  retain  their  full  equipment  of  flagella.  This  view 
was  taken  from  a  slide  preparation  specially  stained,  obtained  from  a  twenty-four 
hours'  growth  on  2  per  cent,  glucose  agar.  Photographed  through  the  micro- 
scope, using  a  2  mm.  oil  immersion  objective  and  acetylene  radiant.  Magnified 
1,200  diameters. 

inch.)  In  addition  to  the  ordinary  flagella  there  are  scattered 
out  the  coverglass  preparation  great  twisted  bodies  called  by  some 
authors  "Giant  Whips."  These  whips  are  different  from  similar 
bodies  (described  by  various  authors),  in  that  they  seem  to  have 
a  small,  round  cell  at  the  end.  This  cell  is  about  0.8  of  a  micron 
in  diameter.  It  is  not  uncommon  to  find  places  where  a  large 
number  of  these  cells  are  arranged  in  a  mass  with  the  "giant 
whips"  extending  outward,  resembling  spirochaetes. 

Plate  No.  5  shows  the  free  spores  and  also  spores  formed  at 
the  end  of  the  bacilli,  which  gives  them  the  appearance  of  drum- 
sticks or  screw  eyes.     The  spores  are  larger  in  diameter  than  the 


CORN. 


451 


rod  forms.  They  are  round,  measuring  from  i  to  i^  microns  in 
diameter.  These  spores  are  very  resistant  to  high  temperatures  on 
account  of  their  thick  walled  membranes. 

Plate  No.  185  shows  a  growth  of  this  organism  in  2  per  cent 
glucose  agar.  The  agar  is  split  in  numerous  places  by  the  gas 
formed.  This  germ  produces  butyric  acid,  mercaptan  and  indol, 
and  we  have  given  it  the  name  of  ''Bacillus  Butyricus  Frumenti," 
a  name  which  indicates  its  origin  in  corn. 


Plate  183 

Photomicrograph  of  the  spores  of  Bacillus  Butyricus  Frumenti,  an  anaerobic 
Dacillus  obtained  from  a  swelled  can  of  corn.  This  germ  produces  a  terminal 
round  spore  which  gives  the  rod  the  appearance  of  a  drumstick  or  screweye  and 
greatly  resembles  Tetanus.  The  spores  are  thick-walled  and  are  very  resistant 
to  high  temperatures.  From  culture  on  2  per  cent,  glucose  agar.  Stained  lightly 
with  carbol  fuchsine.     Magnified  1,200  diameters. 


Plate  No.  186  shows  a  young  vegetating  form  of  another  bacil- 
lus similar  in  some  respects  to  the  species  just  described,  being 
both  anaerobic  and  spore-bearing.  From  its  nature  it  greatly  re- 
sembles Bacillus  Butyricus  (Prazmowski).  It  is  a  beautifully 
flagellated  bacillus,  with  rods  of  varying  length  and  i  micron  wide 
and  called  "Amylobacter,"  from  the  fact  that  when  grown  upon 
media  containing  starch  the  cells  will  stain  blue  with  iodin.  It  is 
more  actively  motile  than  the  other  species  described  and  the  spores 
are  located  generally  in  the  center  of  the  rods,  as  shown  in  plate 
No.  8. 

This  organism  has  the  power  to  cause  the  fermentation  of 
cellulose,  but  we  believe  that  it  is  different  from  Bacillus  Amylobac- 
ter  used  in  pure  cultures  in  the  ripening  of  cheese. 


452 


CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


Plate  184 

Photomicrograph  of  Bacillus  Butyricus  Frumenti,  showing  ordinary  flagella  and 
also  a  bunch  of  giant  whips  greatly  resembling  a  bunch  of  hair.  This  is  an  obli- 
gative  anaerobic  bacillus  found  in  corn  and  was  obtained  from  a  swelled  can 
of  corn.  The  pressure  of  gas  created  by  this  organism  is  enormous,  sufllcient  to 
burst  the  cans.  Stained  by  our  special  method  from  a  young  growth  on  2  per 
cent,  glucose  agar.  Photographed  through  a  2  mm.  oil  immersion  objective  using 
acetylene  radiant.     Magnified  1,200  diameters. 


Plate  185 


Photograph  of  a  test  tube  culture  of  the  anaerobic  Bacillus  Butyricus  Fru- 
menti, on  2  per  cent,  glucose  agar.  The  force  of  gas  was  sufficient  to  split  the 
agar  in  many  places,  forming  pockets  filled  with  gases  of  various  kinds,  such 
as  sulphuretted  hydrogen,  phosphoretted  hydrogen,  hydrogen,  etc.  The  growth 
of  this  germ  in  media  containing  no  sugar  is  not  as  free  in  gas  formation. 


CORN.  453 

Besides  butyric  acid  it  excretes  some  foul  substances,  such  as 
indol  and  sulphuretted  hydrogen.  The  odor  of  canned  corn  in- 
dicating decomposition  by  this  agency  is  abominable.  It  took  sev- 
eral hours  to  remove  the  malodorous  gases  from  the  laboratory. 

These  two  species  were  the  only  ones  found  in  the  swelled  cans, 
which  gave  no  indication  of  leaking.  These  species  are  not  contam- 
inations from  the  atmosphere.     They  were  not  destroyed  in  the 


Plate  186 

Photomicrograph  of  Bacillus  Butyricus  Amylobacter,  an  anaerobic  bacillus 
which  when  grown  on  substances  containing  starch  will  stain  blue  with  iodine. 
The  flagella  are  very  curly  and  were  demonstrated  by  our  own  special  method, 
from  a  24  hours'  growth  on  2  per  cent,  glucose  agar  which  had  been  inoculated 
from  the  juice  of  corn  in  a  swelled  can.  This  organism  is  frequently  found  in 
decomposing  vegetables  and  organic  matter,  and  is  not  found  in  the  air.  Its 
habitat  is  probably  the  soil.     Magnified  1,200  diameters. 


sterilizing  process ;  they  did  not  gain  entrance  to  the  corn  through 
any  leaks;  they  would  not  be  growing  alone  in  pure  cultures  in 
case  they  had  by  chance  gained  entrance  to  the  can.  They  are 
spore-bearing  organisms  and  there  were  no  nori-spore-bearing  or- 
ganisms present.  As  stated  previously,  lactic  acid  and  acetic  acid, 
molds,  yeasts  and  micrococci  are  the  species  which  are  freely  dis- 
tributed in  the  atmosphere,  and  some  of  these  would  most  certainly 
have  been  present  in  case  the  cans  had  leaked.  There  can  be  no 
other  conclusion  than  that  the  sterilizing  process  was  insufficient  to 
prevent  the  growth  and  multiplication  of  anaerobic  bacteria  present 
in  the  corn  itself.     It  might  be  added  that  these  two  species  de- 


454 


CANNING  AND  PRESERVING  OF  FOOD  PRODUCTS. 


Plate  187 

This  beautiful  photomicrograph  shows  the  free  spores  and  the  rods  containing 
spores  of  Bacillus  Butyricus  Amylobacter.  The  spores  are  generally  formed  in 
the  center  of  the  rods  which  cause  them  to  swell  in  the  middle  like  spindles,  hence 
they  belong  to  the  type  called  "Clostridium."  The  spores  are  not  easily  destroyed 
by  heat  and  may  live  in  corn  which  has  received  a  temperature  of  250  degrees 
for  one  hour.     Stained  with  carbol  fuchsine.     Magnified  1,500  diameters. 

scribed  are  commonly  found  associated  with  corn.  A  similar  or- 
ganism to  the  one  shown  in  plate  183  is  often  found  in  spoiled  can- 
ned peas,  but  the  rods  are  much  more  slender  and  the  spore  is  ellip- 
soidal instead  of  round. 


FINIS. 


INDEX  OF  ILLUSTRATIONS.  455 

Illustrations  used  in  this  Volume 

Photomicrographs  by  the  Author 


Plate  Page 

Portrait  of  Author   2 

1.  Frontispiece,  Microscope  10 

2.  Photomicrographic  Camera     19 

3.  Spencer  Microtome    25 

4.  Anaerobic  Pea  Bacillus   38 

5.  Barren   Rods 39 

6.  Bacillus  Phosphorescens    47 

7.  Aspergillus  Fumigatus 51 

8.  "Giant  Whips"  of  Malignant  Oedema 55 

9.  "Giant  Whips"  of  Bacillus  Butyricus  Frumenti  5G 

10.  Bacillus   Prodigiosus,   Showing  Flagella    59 

11.  Bacillus  Cyanogenus,  Showing  Flagella  Gl 

12.  Penicillium  Glaucum  63 

13.  Penicillium    Glaucum    63 

14.  Yellow   Mold    65 

15.  Bacillus  Mesentericus  Vulgatus,  Showing  Flagella   69 

16.  Bacillus  Vulgatus  Viscosus,   Showing  Flagella   70 

17.  Tubercle  Bacilli  from  Sputum    87 

18.  Typhoid  Bacilli,  Showing  Flagella 88 

19.  Bacillus  Mesentericus  Fuscus,  Showing  Flagella   89 

20.  Bacillus  Subtilis,  Showing  Flagella   91 

21.  Bacillus  Mesentericus  Vulgatus,  Showing  Flagella   91 

22.  Bacillus  of  Tetanus,  Showing  Flagella  • 95 

23.  Bacillus  of  Malignant  Oedema,  Showing  Flagella 95 

24.  Bacillus  of  Symptomatic  Anthrax,  Showing  Flagella 99 

25.  Bacillus  of  Asiatic  Cholera,  Showing  Flagella 99 

26.  Yellow    Mold      Ill 

27.  Saccharomyces    Cerevisiae     Ill 

28.  Aspergillus    Glaucus    116 

29.  Aspergillus  Glaucus     117 

30.  Saccharomyces  Ellipsoideus     119 

31.  Mucor  Mucedo     121 

32.  Mucor  Mucedo,  Showing  Conidia   121 

33.  Acetic  Acid  Bacteria 123 

34.  Acetic  Acid  Bacteria    .' 126 

35.  Bacillus  Butyricus  Amylobacter,  Showing  Flagella   129 

36.  Bacillus  Butyricus  Amylobacter,  Showing  Rods  and  Spores  129 

37.  Bacillus  Megatherium,  Showing  Flagella  135 

38.  Bacillus  Megatherium,  Showing  Rods  and  Spores  135 

39.  Bacillus   Lactici  Aceti    139 

40.  Aromatic  Lactic  Acid  Bacilli,  Showing  Flagella 140 

41.  Aromatic  Lactic  Acid  Bacilli,  Showing  Rods  and  Spores  ....  141 

42.  Micro-organisms  in  Lactic    Acid    Generator    Called  "Starto- 

line"        142 

43.  Bacillus  Lactici  Aceti  Longissimus  143 

44.  Asiatic  Cholera  Bacilli,  Showing  Flagella    149 

45.  A  Ptomaine  Bacillus,  Showing  Flagella   (from  mince-meat)  153 

46.  A  Ptomaine    Bacillus,    Showing    Rods    and    Spores     (from 

mince-meat)        153 

47.  Aspergillus  Niger       157 

48.  Aspergillus  Fumigatus        158 

49.  Can  of  Tomatoes  Twenty  Years  Old  159 

50.  Proteus  Sulphurens,  Showing  Flagella  162 

51.  Proteus  Vulgaris,  Showing  Flagella    167 


456  INDEX  OF  ILLUSTRATIONS. 

Plate  Page 

52.  Proteus  Vulgaris,  Showing  "Swarming  Islands"   167 

53.  Proteus  Mirabilis,  Showing  Flagella  171 

54.  Proteus  Mirabilis,  Showing  "Swarming  Island"  171 

55.  Proteus  Zenkeri,  Showing  Flagella   175 

56.  Bacillus  Botulinus,  Showing  Flagella  176 

57.  Bacillus  Botulinus,  Showing  Rods  and  Spores   176 

58.  Bacillus  Enteritidis,  Showing  Flagella   177 

59.  Bacillus  Morbificans  Bovis,  Showing  Flagella   179 

60.  Bacillus  Mallei        181 

61.  Typhoid  Bacillus,  Showing  Flagella   185 

62.  Typhoid  Bacillus,  Showing  Agglutination    (Widal  reaction)  185 

63.  Asiatic  Cholera  Spirilla,  Showing  Flagella  190 

64.  Bacillus  Coli  Communis  191 

65.  Bacillus  Coli  Communis 193 

66.  Bacillus  of  Tetanus,  Showing  Flagella   197 

67.  Bacillus  of  Tetanus,  Showing  Rods  and  Terminal  Spores   . .  197 

68.  Globig's  Potato  Bacillus,  Showing  Flagella  211 

69.  Globig's  Potato  Bacillus,  Showing  Rods  and  Spores 211 

70.  Four  Guinea  Pigs  Used  as  Controls   250 

71.  Six  Guinea  Pigs  and  Two  Rabbits  Fed  on  Preservatives  . .  250 

72.  Section  of  Mucous  Membrane  of  the  Stomach 255 

73.  Section  of  Mucous  Membrane  of  the  Stomach 256 

74.  Section  of  the  Suprarenal  and  Adipose  Tissue   257 

75.  Section  of  the  Spleen 257 

76.  Section  of  the  Heart    258 

77.  Section  of  the  Pancreas    259 

78.  Section  of  the  Kidney 260 

79.  Section  of  the  Kidney    260 

80.  Section  of  the  Kidney 263 

81.  Section  of  the  Kidney  265 

82.  Section  of  the  Kidney    .  .  , 266 

83.  Section  of  the  Suprarenal 266 

84.  Section  of  the  Gall  Bladder 267 

85.  Section  of  the  Mucous  Membrane  of  the  Stomach 268 

86.  Section   of   the  Lung    269 

87.  Section  of  the  Mucous  Membrane  of  the  Stomach  269 

88.  Section  of  the  Intestines    270 

89.  Section  of  the  Glands  of  Mucous  Membrane  of  the  Stomach  272 

90.  Section  of  the  Kidney  273 

91  Section   of   the   Pancreas    274 

92.  Section  of  the  Small  Intestines  . . : 274 

93.  Section  of  Glands  of  the  Mucous  Membrane  of  the  Stomach  275 

94.  Section  of  the  Kidney   276 

95.  Section  of  Gastric  Mucous  Membrane   278 

96.  Section  of  the  Kidney   280 

97.  Section  of  Gastric  Mucous  Membrane   281 

98.  Section  of  Malpigian  Body  of  the  Kidney   282 

99.  Bacillus  Radicico^a        327 

100.  Section  of  a  Nodule 329 

101.  Bacillus  Radicicola        330 

102.  Bacillus  Radicicola,   Showing  Involution  Forms    330 

103.  Nodules  on  the  Roots  of  Peas   331 

104.  Roots  of  a  Pea  Vine,  Showing  Bacteroidal  Nodules  332 

105.  Nitrosomonos  Europea       334 

106.  Green  Pea  Louse    335 

107.  Green  Pea  Louse  (nectarophora  pisi  Kalt)   336 

108.  American  Syrphus  Fly   339 

109.  Lace-Winged   Fly    341 

110.  Eggs  of  Lace-winged  Fly  and  Pea  Lice  Killed  by  Fungous 

disease       342 

111.  Lactic  Acid  Bacillus   349 


INDEX  OF  ILLUSTRATIONS.  457 

Plate  Page 

112.  Bacillus  Butyricus,  Showing  Flagella  (Hueppe)    351 

113.  Bacillus  Butyricus,  Showing  Rods  and  Spores  (Hueppe) 351 

114.  Bacillus  Mesentericus  Vulgatus,  Showing  Flagella  355 

115.  Bacillus  Mesentericus  Vulgatus,  Showing  Rods  and  Spores  355 

116.  Butyric  Acid  Bacillus,  Showing  Flagella   356 

117.  Butyric  Acid  Bacillus,  Showing  Rods  and  Spores 357 

118.  Bacillus  Megatherium,  Chains  in  Sausage  Form  359 

119.  Bacillus  Megatherium,  Showing  Flagella  360 

120.  Bacillus  Megatherium,  Showing  Rods  and  Spores    360 

121.  Bacillus  Prodigiosus,  Showing  Flagella   362 

122.  Bacillus  Subtilis,  Showing  Flagella  365 

123.  Bacillus  Subtilis,  Showing  Spores   365 

124.  Anaerobic  Pea  Bacillus,  Showing  Flagella   366 

125.  Anaerobic  Pea  Bacillus,  Showing  Rods  and  Spores  367 

126.  Non-gas-producing  Pea  Bacillus,  Showing  Flagella   369 

127.  Non-gas-producing  Pea  Bacillus,  Showing  Rods  and  Spores  370 

128.  Bacillus  Mesentericus  Ruber,  Showing  Flagella   371 

129.  Bacillus  Mesentericus  Ruber,  Showing  Rods  and  Spores   . .  372 

130.  Aerobic  Pea  Bacillus,  Showing  Flagella   373 

131.  Aerobic  Pea  Bacillus,  Showing  Rods  and  Spores 373 

132.  Anaerobic  Pea  Bacillus,  Showing  Flagella   374 

133.  Anaerobic  Pea  Bacillus,  Showing  Rods  and  Spores   375 

134.  Bacillus  Butyricus   (Prazmowski),  Showing  Flagella   380 

135.  Bacillus  Butyricus  (Prazmowski),  Showing  Rods  and  Spores  382 

136.  Bacillus  Subtilis  Similis,  Showing  Flagella 384 

137.  Bacillus  Subtilis  Similis,  Showing  Rods  and  Spores    385 

138.  Bacillus  Butyricus  Anaerobic,  Test  Tube  Culture 391 

139.  Bacillus  Butyricus  Anaerobic,  Showing  Flagella   391 

140.  Bacillus  Butyricus  Anaerobic,  Showing  Rods  and  Spores   .  .  392 

141.  Bacillus  Mycoides,  Petri  Dish  Culture  on  Agar 393 

142.  Bacillus  Mycoides,  Showing  Flagella 395 

143.  Bacillus  Mycoides,  Showing  Rods  and  Spores  395 

144.  Bacillus  of  Acetic  Acid   400 

145.  Chromogenic  Tomato  Bacillus,  Showing  Flagella  402 

146.  Chromogenic  Tomato  Bacillus,  Showing  Spores 402 

147.  Mucor  Mucedo,  Showing  Budding  Conidia  404 

148.  Petri  Dish  Culture  of  Mucor  Mucedo  404 

149.  Petri  Dish  Culture  of  Mucor  Mucedo,  Magnified   405 

150.  Mucor  Mucedo,  Showing  Seed  Pods   406 

151.  Mucor  Mucedo,  Showing  Seed  Pods    407 

152.  Aromatic  Tomato  Bacillus,  Showing  Flagella 407 

153.  Aromatic  Tomato  Bacillus,  Showing  Rods  and  Spores 408 

154.  Bacillus  of  Acetic  Acid  or  Mycoderma  Aceti  409 

155.  Bacillus  of  Tomato  Black  Rot  Disease  410 

156.  Vinegar  Bacillus  or  Bacillus  Acidi  Aceti   412 

157.  Bacterium  Prodigiosum,  Showing  Flagella   413 

158.  Chromogenic    Colon-like    Bacillus     of    Tomatoes,    Showing 

Flagella       413 

159.  Bacillus  Megatherium  Similis,  Showing  Flagella   416 

160.  Bacillus  Megatherium  Similis,  Showing  Rods  and  Spores  .  .  416 

161.  Defective  Tin  Plate  423 

162.  Defective  Tin  Plate  424 

163.  Bacillus  Mesentericus  Fuscus,  Showing  Flagella   425 

164.  Bacillus  Mesentericus  Fuscus,  Showing  Rods  and  Spores  . . .  425 

165.  Bacillus  Liodermos,  Showing  Flagella   427 

166.  Bacillus  Liodermos,  Showing  Rods  and  Spores  428 

167.  Bacillus  Bittergenus,  Showing  Flagella   429 

168.  Bacillus  Bittergenus,  Showing  Rods  and  Spores  429 

169.  Bacillus  Mesentericus  Frumenti,  Showing  Flagella  431 

170.  Bacillus  Mesentericus  Frumenti,  Showing  Rods  and  Spores  431 

171.  Bacillus  of  Malodorous  Corn,  Showing  Flagella 433 


458  INDEX  OF  ILLUSTRATIONS. 

Plate  Page 

172.  Bacillus  Mesentericus  Vulgatiis,  Showing  Flagella 435 

173.  Bacillus  Mesentericus  Vulgatus,  Showing  Rods  and  Spores  436 

174.  Bacillus  Butyricus   (Hueppe),  Showing  Flagella   437 

175.  Bacillus  Butyricus  (Hueppe),  Showing  Rods  and  Spores  ...  438 

176.  Bacillus  Mesentericus  Ruber,  Flagellated,  From  Corn   442 

177.  Bacillus  Mesentericus  Ruber,  Showing  Spores  443 

178.  Bacillus  Frumenti  Phenolgenus,  Showing  Flagella 446 

179.  Bacillus  Frumenti  Phenolgenus,  Showing  Rods  and  Spores  446 

180.  A  Can  Exploded  by  Fermentation  448 

181.  Apparatus  for  Testing  Strength  of  a  Can 449 

182.  Bacillus  Butyricus  Frumenti,  Showing  Flagella 450 

183.  Bacillus  Butyricus  Frumenti,  Showing  Spores  and  Rods  . .  451 

184.  Bacillus  Butyricus  Frumenti,  Showing  Flagella  and  "Giant 

Whips"       452 

185.  Test  Tube  Culture  of  B.  Butyricus  Frumenti,  Showing  Gas 

Pockets        452 

186.  B.  Butyricus  Amylobacter,  Showing  Flagella  453 

187.  B.  Butyricus  Amylobacter,  Showing  Rods  and  Spores 454 


Figure  Plate 

1.  Cone  Fine  Adjustment  12 

2.  Mechanical    Stage    13 

3.  Micrometer  Eye-piece       14 

4.  Virtual  Image,  Simple  Microscope   (Carpenter) 14 

5.  Real  Image   (Carpenter)        15 

6.  Principle  of  a  Compound  Microscope  (Carpenter)    15 

7.  Arrangement  of  Lenses  in  a  2  mm.  Oil  Immersion  Objective  17 

8.  Abbe  Condenser       18 

9.  Incubator         20 

10.  Autoclav 21 

11.  Centrifuge       22 

12.  Distilling  Apparatus       22 

13.  Balances        23 

14.  Water-bath        23 

15.  Paraffine-bath       24 

16.  Cornet  Forceps       24 

17.  Novy  Forceps       24 

18.  Bacteria,  Lengthening  and  Dividing   33 

19.  Three  Kinds  of  Bacteria 34 

20.  Varieties  of  Bacteria    35 

21.  Sporulation 37 

22.  Spore  Formation       39 

23.  Position  of  Spores   40 

24.  Hanging-drop  Slid^_^        42 

25.  Germination  of  Spores   43 

26.  Position  of  Flagella    53 

27.  Leuconostoc    Mesenteroides    66 

28.  Anaerobic  Culture  Apparatus  81 

29.  Carbon  Dioxid  Apparatus       106 

30.  Involution  Forms  of  Acetic  Acid  Bacteria   125 

31.  Steam  Retort  With  Water  Attachment  218 

32.  Lady-bird  Beetle       340 

33.  Lace-winged  Fly       34O 

34.  Steam  Retort  With  Water  Attachment  for  Cooling  Cans   387 


OF  THE 

UNIVERSITY 

OF 


Books  of  Reference  Consulted  by  the  Author 


.'     Atkinson,  E.    Suggestion  for  the  Establishment  of  Food  Laboratories. 
U.  S.  Dep't.  of  Agr.     Off.  of  Exp.,  Sta.,  Bui.  17. 
Bowhill,  Thomas.     Mianual  of  Bacteriological  Technique. 
Bulletins  of  Bureau  of  Chemistry  U.  S.  Dep't.  Agr. 
Bulletin  13.     Food  and  Food  Adulterants  1887—1902. 
•-  Bulletin  48.     Methods  of  Analysis  Adopted  by  the  A.  O.  A.  C.  1899. 
r  Bulletin  65.     Provisional   Methods  for  Analysis  Adopted  by  the  A.  0. 
A.  C. 
Burk.     Journal  of  the  American  Chemical  Society,  March  1903. 
Carpenter.     The  Microscope  and  its  Revelations. 
Canner  and  Dried  Fruit  Packer  1903—1904—1905. 
-Conn,  H.  W.     Milk  Fermentation,  U.  S.  Dep't.  Agr.     Off.  of  Exp.  Sta., 
Bui.  9. 

-  Eccles,  R.  G.     Facts  and  Figures  on  Preservatives. 
Fischer,  A.     The  Structure  and  Functions  of  Bacteria. 
Frear,  W.     Apple  Juice.     Fermented  Cider  and  Vinegar. 

-  Fresenius,     Quantitative  and  Qualitative  Analysis. 

Hansen,  E.  Ch.     Untersuchungen  aus  Praxis  der  Gaehrungs-Industrie. 
Harding  &  Nicholson.     Bui.  249,  N.  Y.  Agr.  Exp.  Station,  Geneva,  N.  Y. 
Hutchinson,  Robert  M.  D.     Food  and  Dietetics. 
Johnson,  W.  G.     Science  and  Experiment  as  Applied  to  Canning. 
Jorgensen,  A.     Micro-organisms  and  Fermentation. 

Jorgensen,   A.     Die  Micro-Organismen  der  Gaehrungs  Industrie,   Ken- 
tucky Exp.  Sta.,  Bui.  100. 
Lafar,  Dr.  Franz.     Technical  Mycology. 
V  Ladd,  E.  F.     Food  Products  and  their  Adulteration,  Bui.  53,  57,  63. 
Leach,  Albert  E.     Food  Inspection  and  Analysis. 
Leeuwenhoeck,  A.  von.     Arcana  Naturae  Detecta. 
Lehmann  &  Neumann.    Atlas  and  Principles  of  Bacteriology. 

-  Lehmann,  H.     Select  Methods  of  Food  Analysis. 
^  Novy,  F.  G.     Laboratory  Work  in  Bacteriology. 

Oppenheimer,  C.     Ferments  and  their  Action. 

Pasteur,  L.     Studies  in  Fermentation. 

Potter,  Samuel  O.  L.     Quiz  Compends  Materia  Medica. 

Prcscott,  S.  C.  &  Underwood,  W.  S.     Micro-organisms  and  Sterilization. 

Processes  in  the  Canning  Industry. 
Prescott  &  Winslow.     Elem.ents  of  Water  Bacteriology. 
Reports  of  the  Department  Committee,  London. 
Richmond,  Henry  Droop,  Dairy  Chemistry. 
Rideal,  S.     Disinfection  and  Preservation  of  Food. 
Sanderson,  J.  G.     Science  and  Experiment  as  Applied  to  Canning. 
Sternberg,  G.  M.,  M.  D.     A  Text  Book  of  Bacteriology. 
Traphagen.     Journal  of  the  American  Chemical  Society,  March  1903. 
Tyndall.     Floating  Matter  of  the  Air. 
Van  Tieghem.     Leuconostoc  Mesenteroides. 
Vaughan  &  Novy,     Cellular  Toxins. 
Wiley,  H.  W.     Chemistry,  Bui.  of  Chemistry,  U.  S.  Dep't.  Agr.,  Bui.  53. 


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INDEX 


Abbe    Condenser i8 

Acetic  Acid  Fermentation  .  .  120 

Agar  Culture    Media 76 

Agglutination  of  Typhoid   .  . 

Bacilli       185 

Alcoholic   Fermentation    ....  120 
Alum  in  Blanching  Bath.  .  .  353 
American  Syrphus   Fly.  .  .  .   339 
Anaerobic    Culture    Appara- 
tus           81 

Anaerobic  Pea  Bacilli 

366,  367,  374,  391 

Anguilula  Aceti 125 

Antiseptics  (Miquel's  Table)  294 
Aspergillus   Fumigatus    .... 

49.  5I'    158 

Aspergillus  Glaucus    ..    116,   117 

Aspergillus  Niger 157 

Autoclav     21 

Bacillus 

Aceticus   124 

Acidificans  Longissimus .  .    143 

Acidi  Lactici 137,  349 

Actinobacter    (Duclax)    .  .   67 

Albus    61 

Alvei   339 

Anaerobic  Pea  Bacillus .  . 

38,  366 

Aromatic  Lactic 140 

Bittergenus    429 

Botulinus    176 

Butyricus  (Hueppe)  351,  437 
Butyricus  Prazmowski  .  .  380 
Butyricus  Amylobacter   .  . 

129,  453 

Butyri  Fluorescens  (Lafar  61 
Butyricus    Frumenti     56,  450 

Capsulatus   51 

Cholera,  Asiatic  ....  99,  189 
Coli  Communis  ....   163,  191 

Cyanogenus   61 

Diphtheria  Columbarum     200 

Enteritidis 175,  177 

Fluorescens,  Liquef acians .  67 
Fluorescens  Putidus   ....     61 

Fluorescens  Tenuis 61 

From    Poisonous     Mince 

Meat   153 


Frumenti  Phenolgenus  .  .  446 
Lactis    Saponacei  (Weig- 

mann)    6y 

Lactis      Viscosus     (Ada- 

metz)    6y 

Liodermos    427 

Mallei 179 

Megatherium  67,  135,  359,  416 
Mesentericus  Frumenti  .  •  431 
Mesentericus  fuscus  51,  89,  525 
Mesentericus  Ruber.  .  51,  371 
Mesentericus  Vulgatus  .  . 
....51,  67,  69,  91,  354,  435 

Morbificans  Bovis 177 

Mycoides    393 

Of  Acetic  Acid    123,  400,  409 

Of  Diphtheria   163 

Of      Malignant     Oedema 

(Novy)     55,  95 

Of  Malodorous  Corn  ....  433 

Of  Sour  Corn 442 

Of  Tomato  Black  Rot  .  .  410 

Of   Tuberculosis 87 

Pituitosi  (Loeffler)   6y 

Potato  (Globig) 211 

Prodigiosus   59,  361 

Proteus  Mirabilis   .  .    155,  171 

Proteus  Sulphurans 162 

Proteus  Vulgaris  155,  165,  167 
Proteus  Zenkeri  ....  155,  175 

Pyocyaneus 61 

Radicicola   327,  330 

Subtilis 91,  362 

Symptomatic  Anthrax  .  .     99 

'I'etanus 95,  ^95 

Thermophilus  (Miquel)  .  .     49 

Typhoid 8S,  182 

Viridans    61 

Viscosus  Sacchari 67 

Vulgatus  Viscosus 70 

Bacteria 

Barren  Rods   139 

Description   and    Classifi- 
cation         ^^ 

Forms 34 

Influence  of  Electricity  on 

47,  223 

Influence  of  Light  on  .  .  .     51 


464 


INDEX 


Influence  of  Temperature 

on    48 

Life  History 36 

Motility    53 

Multiplication  of 33 

Nature  and  Composition      44 
Oxygen  Requirements  .  .     45 

Sporulation    37 

Varieties   35 

Bacterium 

Aceti 124 

Kutzingianum   124 

Lactis   137 

Lvudwigi   49 

Pasteurianus    124 

Phosphorescens     47 

Prodigiosum    57 

Syncyaneum       57 

Synxanthum  (Fuchs)    ....    57 

Termo    149 

Bacteroids    325 

Balances   23 

Benzoic  Acid 286 

Benzoic  Acid  in  Fruits   .  .  .   228 
Bitterness  in  Fruit  Products  133 

Blanching  Process 353 

Blood  Serum 78 

Borax   292 

Boracic  Acid   292 

Bouillon  Culture  Media  ....     73 

Bread  Media   78 

Brownian  Motion 53 

Butter    Making 141 

Butyric  Acid  Bacillus 356 

Butyric    Fermentation   127,  361 
Calcium    Sterilizing  System 

• 219,  317 

Can  Testing  Apparatus   .  .  .  449 
Canned  Goods  not  Affected 

by  Age 159 

Canning      Factory     Equip- 
ment        314 

Canning    Factory   Location  314 

Canning  History 311 

Capping  Machines   316 

Caramel,  Detection  of  ....   309 

Carbol  Fuchsine 97 

Catsup,   Tomato 227 

Centrifuge    22 


Cherries,  Containing  Salicy- 
lic   Acid    229 

Chili  Sauce    227 

ChilHng  Canned  Gnods  ....  219 
Chromogenic  Bacteria   ....      56 
Cleanliness  in     Manufactur- 
ing        215 

Coal  Tar  Dyes,  Detection  of  306 
Coating,  Inside  for  Cans  .  .  310 

Cochineal   306 

Cold  Storage  System 48 

Colors,  Artificial 303 

Condiments,   Requiring  Pre- 
servatives         236 

Cone  Fine  Adjustment  ....     12 
Copper  in  Peas,  Beans,  as- 
paragus. Pickles,  etc. .  .   307 

Corn   418 

Coverglasses,  Cleaning  of  82,  93 
Crab  Apples  Containing  Sa- 
licylic Acid 229 

Cultural  Methods  .  .  .  ^  .  .  82,  93 
Currants  Containing  Salicy- 
lic Acid 229 

Discontinuous   Sterilization    222 

Disinfectants    294 

Distilling  Apparatus 

Dulcin         

Enamel  for  Coating  Inside  of 

Cans      310 

Ensilage   146 

Entomopluthora  Aphidis  .  .  341 
Equipment -for  Canning  Fac- 
tory       315 

Fermentation     104 

Flagella    53 

Flagella,  Staining  Method .  .     8y 
Formaldehyde,    Formed   by 

Oxidation 52 

Formaldehyde,   Detection  of  289 
Forceps  for  Staining  Cover 

Glass   Preparations  ...     24 

Formic   Acid 361 

Fruits,     Natural     Preserva- 
tives in   228 

Fruit  Butters 227 

Gelatin  Media 75 

Giant  Whips    55 

Glucin,  as  Sweetener 300 


INDEX 


465 


Grapes,  Salicylic  Acid  in    .  .    229 
Green  Gages,  Salicylic  Acid 

in   228 

Guinea  Pigs  Fed  on  Preserv- 
atives        249 

Hanging-drop  Culture  Meth- 
od          42 

Hay  Bacillus 91,  362 

Heat,  Action  on  Spores  .... 

51.  209,  375.436 

Incubator 20 

Indol,  Production  of 149 

Inside  Coating  for  Cans  ...  310 
Inside   Testing   Thermome- 
ters        366 

Isolating  Bacteria,   Method  368 
Laboratory    Equipment  ...      11 

Lace  Winged  Fly 341 

Lactic  Bacteria 137 

Lactic  Fermentation  of  On- 
ions,     Meat,      Pickles, 

Olives,  etc 143 

Leaks,    Danger  of    Re-Pro- 
cessing        150 

Lenses 14 

Leuconostoc  Mesenteroides     66 

Mechanical  Stage 13 

Micrococcus     Panhistophy- 

ton  Ovatum 339 

Micrometer  Eyepiece 14 

Microscope 11 

Microtome   25 

Milk,  Preservatives  Formed 

in 230 

Molasses,  Fermentation  of .  .     70 
Mold,  Yellow  Colored  ....     65 

Molds,  Pathogenic 155 

Mordant   for   Staining   Fla- 

gella    97 

Mucinous  Products  of  Bac- 
teria      66,  356 

Mucor  Mucedo 121,  404 

Muddy   Liquor   on   Canned 

Peas    354 

Mycoderma  Aceti 123 

Nitrifying  Bacteria  .  .  .  325,  ^^^ 
Nitrobacter   (Winogradsky)   335 
Nitrogen  Fixing  Bacteria .  .    .  . 
325.  327 


Nitrogen  Sources 326 

Nitrosomonas  Europea  .  .  .  334 
Nitrosomonas  Javanensis..    334 

Objectives 11,  13 

Oil  Bath  for  Sterilization  .  .  220 

Oxygen    45 

Paraffine  Bath 24 

Pathological  Work  on 
Guinea  Pigs  and  Rab- 
bits       253 

Peas    324 

Pea  Canning   347 

Pea  Green  Louse   335 

Pea  Planting   346 

Penicillium      Glaucum      i  n 

Cheese    61 

Pepsin,    Experiments    With 

....... .  234,  243,  247 

Photomicrographic  Camera  19 
Photomicrographic  Methods  103 
Plums,  salicylic  acid  in   ....   229 

Potato  culture  media   yy 

Preservatives       225 

Preservatives,  discussion  on  .  283 
Preservatives,      formed      by 

heat      230 

Preservatives,  formed  by  mi- 
cro-organisms    230 

Preservatives,  formed  by  sun- 
light          230 

Preservatives,       natural       in 

fruits      228 

Preservatives  natural  in  veg- 
etables       229 

Preservatives,   testimony  be- 
fore the  British  Parlia- 
mentary Committee   .  .  .   232 
Preservatives  fed  to  animals  249 
Processing,  canned  goods  .  . 

208,  387 

Process  kettles,  cold  water  at- 
tachment       218 

Ptomaines  and  toxins 202 

Ptomaine  poisoning 162 

Ptomaines,  methods  of  ex- 
traction       205 

Pulses,  analyses  of 346 

Putrefaction     146,  161 

Raw  material,  selection  of  .  322 


466 


INDEX 


Red  color    formed    on    food 

products      59.  361 

Resistance  of  spores   

51,  209,  375,  436 

Root  bacillus,  mycoides  ....  393 
Saccharin  .  .  297,  378,  419,  444 
Saccharomyces  cerevisiae 
Saccharamyces  cerevisiae  .  .  1 1 1 
Saccharomyces  ellipsodeus .  .  119 
Saccharomyces  pastorianus  .    141 

Salicylic- :acid 288,  244 

Salicylic  acid  in  fruits 229 

Sauces     227 

Sauer  kraut 144 

Skatol,  formation  of 150 

Slime-producing       organism 

66,  356 

Sour  corn 438 

Sour  corn,  cause  of 420 

Sour  corn,  method  of  separ- 
ating     . 421,  441 

Sour  peas 348 

Sour  peas,  bacteria  of 369 

Sour  tomatoes   401 

Spoilage  of  food  products  .  .     J2 

Spoilage  of  peas 379,  388 

Spontaneous     decomposition 

of  fruit   106 

Spontaneous  generation  the- 
ories     104 

Spores,  characteristics  of  37,  42^ 

Spores,  formation  of 37 

Spores,  germination  of    .  .42,  43 
Spores,    heat-resistance, .... 

.••    51.  209,  375,  436 

Spores,  position  in  the  rod .  .     40 

Staining  agents    97 

Staining  methods 82 

Staining,  contact  method  ...     84 
Staining,   Gramm's  method.      84 
Staining  of  anaerobes  (Duck- 
wall)      93 

Staining  of  flagella    (Duck- 
wall) 87 

Staining  of  tubercle  bacilli  .     84 

Starch      422 

Starch,  detection  of 309 


''Startoline,"  lactic  acid  gen- 
erator       

Sterilization    208, 

Sterilization,  determination 
of       

Streptococcus  bombycis  .... 

Streptococcus  hollandicus   .  . 

Sugar   378, 

Sulphites 

Sulphurous  acid   

''Sweating  of-  raw  material" 

349. 

Sweeteners,  artificial   

Swelled  corn 

Table  of  antiseptics  (Miquel) 

Table  of  apparatus  and  chem- 
icals        

Table  of  processes,  peas   .  .  . 

Table  of  reagents 

Table  of  temperature  records, 
peas      

Tables  of  weights  of  Guinea 
pigs   .  .  .  .252,  262.  271, 

Tin  plate,  defective 

Tomatoes    ...-.-.  ............  .  .  . 

Tomato  bacillus   ...'.- 

Tomato  black  rot  disease   .  . 

Tomatoes,  scalding  method .  . 

Tomatoes,  swells   

Tumeric,  detection  of 

Vacuum  jar  for  tomatoes   .  . 

Vacuum  machinery  ...    118, 

Vacuum,  the  theory  of   .... 

Venting       

Vibrio  cholerae  Asiaticae   .  . 

Vibrio  Xanthogenus  (Fuchs) 

Vinegar,  bacteria  of 

Vinegar  eels   

Vinegar-making 'methods    .. 

Vining  machinery  ....   317, 

Viscous  products  of  bacteria 
66, 

Waste  material,  disposition  of 

Water  bath   

Whortleberries,  benzoic  acid 

in 
Widal's  reaction 


142 
363 

213 

339 
67 

443 
•301 
301 

378 
297 

447 
294 

26 

376 

28 

368 

279 

243 
398 
402 
408 
399 
415 
307 
403 
221 

T13 
221 
149 

57 
123 

125 

T24 

346 

356 

215 
23 

228 
185 


0  ^_/f 


.noK  IS  DTJE  ON  THE  LAST  DATE 
■'^^^^^''sTA^ED  BELOW 

AN    INITIAL    *^l"''^,,uRETO   BCTUBN 
=  ir   ASSESSED   FOB  ^'^'^"T^^.s,  pENAl-TV 

OVERDUE. 


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